This question is from trigonometry topic – trigonometric ratios on complementary angles in which we have been asked to prove that sinθ cos(90°-θ) cosθ/sin(90°-θ) + cosθ sin(90°-θ) sinθ/cos(90°-θ) = 1
RS Aggarwal, class 10, chapter 12, question no 5[iii]
Hope it helps you.