Which of the following is not a symmetrical figure?
- (a)
- (b)
- (c)
- (d)
Show solution
Solution: Correct answer is (d).
Class 7 Mathematics · 124 questions · 95 with answers
Which of the following is not a symmetrical figure?
Solution: Correct answer is (d).
In the word “MATHS” which of the following pairs of letters shows rotational symmetry
Solution: Correct answer is (b).
The angle of rotation for the figure 12.2 is
Solution: Correct answer is (C) In Examples 4 to 6, fill in the blanks to make it a true statement.
The figure 12.3 has ________ vertices, __________ edges and __________ faces.
Solution: 10, 15, 7 Fig. 12.3 15-04-2018
The adjoining net in Fig. 12.4 represents a _________.
Solution: Cube
Rotation turns an object about a fixed point. This fixed point is called _______.
Solution: centre of rotation. Fig. 12.4 In Examples 7 to 9, state whether the statements are True or False.
A net of a 3-D shape is a sort of skeleton - outline in 2-D, which, when folded results in the 3-D shape.
Solution: True
A regular pentagon has no lines of symmetry.
Solution: False Translation Rotation Reflection A translation slides A rotation turns a A reflection flips a a figure along the figure around a figure across a line direction of a line point, called the to create a mirror without turning. centre of rotation. image.
Order of rotational symmetry for the figure 12.5 is 4. Fig. 12.5
Solution: False 15-04-2018
Draw all the lines of symmetry for the following letters if they exist. Solution
State whether the figure 12.6 shows rotational symmetry. If yes, then what is the order of rotational symmetry?
Solution: The given figure shows rotational symmetry. The order of symmetry = 4, Fig. 12.6 which is clear from the following figure: Note: The dot is placed just to indentify different positions of the figure.
Identify the following figures:
Solution: (i) Rectangular Pyramid (ii) Triangular Prism
Construct a triangle PQR such that PQ = 6 cm, QR = 7 cm and PR = 4.5 cm. Solution Steps:
Draw the top, the front and the side views of the following solid figure made up of cubes. Fig. 12.9 15-04-2018
Solution: Desired views are shown in Fig. 12.10 below Fig. 12.10 Nature provides many beautiful examples of symmetry, such as the wings of a butterfly and a peacock or the petals of a flower. Symmetric objects have parts that are congruent. A figure has line symmetry if you can draw a line through it so that the two sides are mirror images of each other. The line is called the line of symmetry.
Given a line l and a point M on it draw a perpendicular MP to l where MP = 5.2cm and a line q parallel to l through P. 15-04-2018 Solution Fig. 12.11 Steps :
Determine the number of edges, vertices and faces in the Fig. 12.12. Fig. 12.12
Solution: Understand and Explore the Problem 15-04-2018 • What information is given in the question? A square pyramid. • What are you trying to find? The number of edges. vertices and faces. • Is there any information that is not needed? The measure of the edges are not needed. Plan a Strategy • Recall the definitions of edges, vertices and faces of a 3-D figure and try to co-relate them to the figure given above. Solve • The different plain regions are called faces. Hence, there are 5 faces. • The line segments formed, where the faces meet are called edges. Hence, there are 8 edges. • Edges meet at a point which are called vertices. Hence, there are 5 vertices. • Therefore, a square pyramid has 5 faces, 5 vertices and 8 edges. Revise • Try to find the number of vertices and edges of a cuboid. Can you see a pattern emerging based on your findings? you can observe that F+V=E+2 Where F,V,E denote number of faces, number of vertices and number of edges respectively of such solids. This is known as ‘EULER’s FORMULA’. You’ll study this concept in your next class. Try to find the number of edges, vertices and faces in some more solids and explore the pattern, if any. 15-04-2018 A figure has rotational symmetry if you can rotate the figure around some point so that it coincides with itself. The point is the centre of rotation, and the amount of rotation must be less than one full turn, or 360°. 7-fold and 6-fold rotational symmetry mean that the figures coincide with themselves 7 times and 6 times respectively, within one full turn. 7-fold rotational symmetry 6-fold rotational symmetry In each of the Questions 1 to 26, there are four options, out of which one is correct. Choose the correct one.
A triangle can be constructed by taking its sides as:
Across 6.
A triangle can be constructed by taking two of its angles as:
7.
The number of lines of symmetry in the figure given below is:
This question refers to a figure in the original PDF.
8.
The number of lines of symmetry in Fig. 12.14 is
This question refers to a figure in the original PDF.
9.
The order of rotational symmetry in the Fig. 12.15 Fig. 12.14 given below is
This question refers to a figure in the original PDF.
(b) 8
(a) 4
(c) 6
The order of rotational symmetry in the figure 12.16 given below is
This question refers to a figure in the original PDF.
(b) 2 Fig. 12.16
The name of the given solid in Fig 12.17 is:
This question refers to a figure in the original PDF.
(b) rectangular pyramid
The name of the solid in Fig. 12.18 is:
This question refers to a figure in the original PDF.
(c) triangular prism
All faces of a pyramid are always: Fig. 12.18
This question refers to a figure in the original PDF.
(d) None of these
A solid that has only one vertex is
(c) Cone
Out of the following which is a 3-D figure?
(b) Sphere
Total number of edges a cylinder has
(c) 2
A solid that has two opposite identical faces and other faces as parallelograms is a
(a) prism
The solid with one circular face, one curved surface and one vertex is known as:
(a) cone
If three cubes each of edge 4 cm are placed end to end, then the dimensions of resulting solid are:
(a) 12 cm × 4 cm × 4 cm
When we cut a corner of a cube as shown in the figure 12.19, we get the cutout piece as :
This question refers to a figure in the original PDF.
(c) triangular pyramid
If we rotate a right-angled triangle of height 5 cm and base 3 cm about its height a full turn, we get
(a) cone of height 5 cm, base 3 cm
If we rotate a right-angled triangle of height 5 cm and base 3 cm about its base, we get:
(d) cone of height 3 cm and base 5 cm
When a torch is pointed towards one of the vertical edges of a cube, you get a shadow of cube in the shape of
(b) rectangle but not a square
Which of the following sets of triangles could be the lengths of the sides of a right-angled triangle:
(c) 1.5 cm, 3.6 cm, 3.9 cm
In which of the following cases, a unique triangle can be drawn
(c) XY = 5 cm, ∠X = 45° and ∠Y = 60°
Which of the following has a line of symmetry ?
(c)
Which of the following are reflections of each other?
(a)
Which of these nets is a net of a cube?
(b)
Which of the following nets is a net of a cylinder ?
(c)
Which of the following letters of English alphabets have more than 2 lines of symmetry?
(b)
Take a square piece of paper as shown in figure (1). Fold it along its diagonals as shown in figure (2). Again fold it as shown in figure (3). Imagine that you have cut off 3 pieces of the form of congruent 15-04-2018 isosceles right-angled triangles out of it as shown in figure 4. (1) (2) (3) (4) On opening the piece of paper which of the following shapes will you get?
(a)
Which of the following 3-dimensional figures has the top, side and front as triangles?
(c)
In an isosceles right triangle, the number of lines of symmetry is ________.
one
Rhombus is a figure that has ______lines of symmetry and has a rotational symmetry of order _______.
2,2
__________ triangle is a figure that has a line of symmetry but lacks rotational symmetry.
Isosceles
__________ is a figure that has neither a line of symmetry nor a rotational symmetry. 15-04-2018
Quadrilateral
__________ and __________ are the capital letters of English alphabets that have one line of symmetry but they interchange to each other when rotated through 180°.
M and W
The common portion of two adjacent faces of a cuboid is called __________.
Edge
A plane surface of a solid enclosed by edges is called __________ .
Face
The corners of solid shapes are called its __________.
Vertices
A solid with no vertex is __________.
Sphere
A triangular prism has __________ faces, __________ edges and __________ vertices.
5, 9, 6
A triangular pyramid has __________ faces, __________ edges and __________vertices.
4, 6, 4
A square pyramid has __________ faces, __________ edges and __________ vertices.
5, 8, 5
Out of __________ faces of a triangular prism, __________are rectangles and __________ are triangles.
5, 3, 2
The base of a triangular pyramid is a __________.
Triangle
Out of __________ faces of a square pyramid, __________ are triangles and __________ is/are squares.
5, 4, 1
Out of __________ faces of a rectangular pyramid __________ are triangles and base is __________.
5, 4, rectangle
Each of the letters H, N, S and Z has a rotational symmetry of order __________.
2
Order of rotational symmetry of a rectangle is __________.
2
Order of rotational symmetry of a circle is __________.
Infinite
Each face of a cuboid is a __________.
Rectangle
Line of symmetry for an angle is its __________.
Bisector
A parallelogram has __________ line of symmetry. 15-04-2018
No
Order of rotational symmetry of is _________.
8
A __________ triangle has no lines of symmetry.
Scalene
Cuboid is a rectangular_________ .
Prism
A sphere has __________vertex, __________edge and __________curved surface.
0, 0, 1
is a net of a __________. → Circumference of circle = ______.
Cone
is a net of a __________.
Triangle Prism
Order of rotational symmetry of is __________.
1
Identical cubes are stacked in the corner of a room as shown below. The number of cubes that are not visible are _________. Fig. 12.20 15-04-2018 In Questions from 59 to 92, state whether the statements are True or False.
This question refers to a figure in the original PDF.
10
We can draw exactly one triangle whose angles are 70°, 30° and 80°.
False
The distance between the two parallel lines is the same everywhere.
True
A circle has two lines of symmetry.
False
An angle has two lines of symmetry.
False
A regular hexagon has six lines of symmetry.
True
An isosceles trapezium has one line of symmetry.
True
A parallelogram has two lines of symmetry.
False
Order of rotational symmetry of a rhombus is four.
False
An equilateral triangle has six lines of symmetry.
False
Order of rotational symmetry of a semi circle is two.
False
In oblique sketch of the solid, the measurements are kept propor- tional.
False
An isometric sketch does not have proportional length.
False
A cylinder has no vertex.
True
All the faces, except the base of a square pyramid are triangular.
True
A pyramid has only one vertex.
False
A triangular prism has 5 faces, 9 edges and 6 vertices.
True
If the base of a pyramid is a square, it is called a square pyramid.
True
A rectangular pyramid has 5 rectangular faces.
False
Rectangular prism and cuboid refer to the same solid.
True
A tetrahedron has 3 triangular faces and 1 rectangular face.
False
While rectangle is a 2-D figure, cuboid is a 3-D figure.
True
While sphere is a 2-D figure, circle is a 3-D figure.
False
Two dimensional figures are also called plane figures.
True
A cone is a polyhedron. 15-04-2018
False
A prism has four bases.
False
The number of lines of symmetry of a regular polygon is equal to the vertices of the polygon.
True
The order of rotational symmetry of a figure is 4 and the angle of rotation is 180° only.
False
After rotating a figure by 120° about its centre, the figure coincides with its original position. This will happen again if the figure is rotated at an angle of 240°.
True
Mirror reflection leads to symmetry always.
False
Rotation turns an object about a fixed point which is known as centre of rotation.
True
Isometric sheet divides the paper into small isosceles triangles made up of dots or lines.
False
The circle, the square, the rectangle and the triangle are examples of plane figures.
True
The solid shapes are of two-dimensional.
False
Triangle with length of sides as 5 cm, 6 cm and 11 cm can be con- structed.
False
Draw the top, side and front views of the solids given below in Figures 12.21 and 12.22:
This question refers to a figure in the original PDF.
(i) Fig. 12.21
(ii) Fig. 12.22 15-04-2018 Three-dimensional figures often look different from different points of view. You can use centimetre cubes to help you visualize and sketch three- dimensional figures. 1. Use centimetre cubes to build the three-dimensional figure at right. 2. Now view the figure from the front and draw what you see.Then view the figure from the top and draw what you see. Finally, view the figure from the side and draw what you see. Front Top Side 1. How many cubes did you use to build the three-dimensional figure? 2. How could you add a cube to the figure without changing the top view ? 3. How could you remove a cube from the figure without changing the side view ?
Draw a solid using the top. side and front views as shown below. [Use Isometric dot paper].
Construct a right-angled triangle whose hypotenuse measures 5 cm and one of the other sides measures 3.2 cm.
Construct a right-angled isosceles triangle with one side (other than hypotenuse) of length 4.5 cm. 15-04-2018
Draw two parallel lines at a distance of 2.2 cm apart.
Draw an isosceles triangle with each of equal sides of length 3 cm and the angle between them as 45°.
Draw a triangle whose sides are of lengths 4 cm, 5 cm and 7 cm.
Construct an obtuse angled triangle which has a base of 5.5 cm and base angles of 30° and 120°.
Construct an equilateral triangle ABC of side 6 cm.
By what minimum angle does a regular hexagon rotate so as to coincide with its origional position for the first time?
60° OSKNRKPNOV ONQL Figure Number of Lines of Symmetry Order of Rotation of Symmetry a 1 1 b 1 1 c 1 1 d 2 2 e 1 2 f 0 1 g 1 1 h 0 3 i 4 4 j 1 1 k 0 1 l 1 1 m 0 2 n 0 1 o 1 1 p 1 1 q 1 1 r 0 3 s 3 3 t 1 1 u 10 10 v 3 3 w 0 1
In each of the following figures, write the number of lines of symme- try and order of rotational symmetry. Fig. 12.23 [Hint: Consider these as 2-D figures not as 3-D objects.]
This question refers to a figure in the original PDF.
In the figure 12.24 of a cube,
(i) Which edge is the intersection of faces EFGH and EFBA?
(ii) Which faces intersect at edge FB? 15-04-2018
(iii) Which three faces form the vertex A?
(iv) Which vertex is formed by the faces ABCD, ADHE and CDHG? (v) Give all the edges that are parallel to edge AB. (vi) Give the edges that are neither parallel nor perpendicular to edge BC. (vii) Give all the edges that are perpendicular to edge AB. (viii) Give four vertices that do not all lie in one plane.
Draw a net of a cuboid having same breadth and height, but length Fig. 12.24 double the breadth.
This question refers to a figure in the original PDF.
Draw the nets of the following:
Draw a net of the solid given in the figure 12.25: Fig. 12.25
This question refers to a figure in the original PDF.
Draw an isometric view of a cuboid 6 cm × 4 cm × 2 cm.
The net given below in Fig. 12.26 can be used to make a cube.
This question refers to a figure in the original PDF.
Draw the net of triangular pyramid with base as equilateral triangle of side 3 cm and slant edges 5 cm.
Draw the net of a square pyramid with base as square of side 4 cm and slant edges 6 cm.
Draw the net of rectangular pyramid with slant edge 6 cm and base as rectangle with length 4 cm and breadth 3 cm. 1. Use centimetre cubes to build a figure that has the front, tops and side views shown. Front Top Side 2. You can build the figure by first making a simple figure that matches the front views. 3. Now add cubes so that the figure matches the top view. 4. Finally, remove cubes so that the figure matches the side view. Check that the front and top views are still correct for the figure that you built. Discuss whether there is another step-by-step method for building the above figure. If so, is the final result the same. 15-04-2018
Find the number of cubes in each of the following figures and in each case give the top, front, left side and right side view (arrow indicating the front view).
Draw all lines of symmetry for each of the following figures as given below: (a) (b) (c) 1. Use centimetre cubes to build each three-dimensional figure given below. Then sketch the front, top and side views.
How many faces does Fig. 12.27 have? Fig. 12.27
This question refers to a figure in the original PDF.
Trace each figure. Then draw all lines of symmetry, if it has.
Tell whether each figure has rotational symmetry or not.
Draw all lines of symmetry for each of the following figures.
Tell whether each figure has rotational symmetry. Write yes or no.
Does the Fig. 12.28 have rotational symmetry ? Fig. 12.28 15-04-2018
This question refers to a figure in the original PDF.
The flag of Japan is shown below. How many lines of symmetry does the flag have? Fig. 12.29
This question refers to a figure in the original PDF.
Which of the figures given below have both line and rotational symmetry?
Which of the following figures do not have line symmetry?
Which capital letters of English alphabet have no line of symmetry? 1. Crossword Puzzle Solve the crossword and fill the given box across, downward as per the mentioned clue in the boxes. Across Down 1. The sketch of a solid in 2. The fixed point around which the measurements which the object is rotated. are kept proportional. 3. Two or more lines which 4. The solid shape which does remain apart at a constant not have a vertex or edge. distance, even if extended indefinitely. 5. The 3-D figure which has a 6. The line where two faces of Joker’s cap. a 3-D figure meet. 7. A 2-D figure which has 8. The skeleton 2-D figure unlimited lines of symmetry which when folded results and an infinite order of in a 3-D shape. rotation. 9. The solid which has 5 faces- 10. Shadow of a cube. 3 of which are rectangles and 2 are triangles. 15-04-2018 2. Crazy Cubes Make four cubes with paper and tape, numbering each face as shown. The goal is to line up the cubes so that 1, 2, 3 and 4 can be seen along the top, bottom, front and back of the row of cubes. They can be in any order, and the numbers do not have to be right side up. 15-04-2018