This ques is from the Book- ML Aggarwal
Board- ICSE
Publication- Avichal
Chapter- Trigonometric Identities
Chapter number-18
1). 2(sec2 35°- cot 2 55°) – cos 28° cosec 62°/tan 18° tan36° tan 30° tan 54° tan 72°. (ii)[cosec2 (90°- theta) – tan2 theta] / 2 (cos2 48° + cos2 42°) – 2tan2 30° sec2 52° sin2 38°/cosec2 70°- tan2 20°
Question no. 10, ML Aggarwal, ICSE board
Given,