Question

If alpha and beta are complementary angles then cos square alpha + cos square beta is equal to :

Answer 1

alpha+beta=pi/2
There fore beta = pi/2-alpha

sin^2 (pi/2- alpha) + sin^2 (pi/2-beta) = sin^2 (beta) +cos^2 (beta) = 1

answer is 1

Answer 2

Hey there !!!!!

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α,β are a pair of complementary angles.

Complementary angles are angles whose sum = 90°

α+β= 90°

β= 90-α

=cos²α+cos²β

= cos²α+cos²(90-α)

But cos(90-α) =sinα

So cos²(90-α)=sin²α

= cos²α+cos²(90-α)

= cos²α+sin²α

= 1

                          cos²α+cos²β = 1

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Hope this helped you.................