Q3Short answer
cosec 20° – sec 20° = sin 20° − cos 20° 3 1 3 cos 20° – sin 20° cos 20° – sin 20° = = 4 2 2 sin 20° cos 20° 2sin 20° cos 20° sin 60° cos 20° – cos 60° sin 20° = 4 sin 40° (Why?) sin (60° – 20°) = 4 =4 (Why?) sin 40° TRIGONOMETRIC FUNCTIONS 41