Mathematics for IGCSE & O level - Pythagoras' Theorem And Trigonometry (Section 7 - No. 17)
What is the relationship between the sine and cosine of complementary angles?
They are equal.
They are reciprocals of each other.
They are inverses of each other.
They add up to 1.
Explanation
sin(θ) = cos(90° - θ)