Question

Sin (90° – A) and cos A are​

Answer 1

Answer:

The complementary angle equals the given angle subtracted from a right angle, 90°. For instance, if the angle is 30°, then its complement is 60°. Generally, for any angle θ, cos θ = sin (90° – θ).

sin (a - b) = sin a.cos b - sin b.cos a

sin (90 - a) = sin 90.cos a - sin a cos 90.

Since sin 90 = 1, and cos 90 = 0, therefor,

sin (90 - a) = cos a

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