This question is from trigonometry topic -trigonometric ratios on complementary angles in which we have to Express the following in terms of T-ratios of angles lying between 0° and 45°: cosec54° + sin72°
RS Aggarwal, Class 10, chapter 12, question no 8(iv)
We have,
cosec(90°−θ)=secθ and sin(90°−θ)=cosθ
csc54°=csc(90°−36°)=sec36°
sin72°=sin(90°−18°)=cos18°
∴csc54°+sin72°=sec36°+cos18°