Question

cos square theta + cos square ( 90 -theta)

Answer 1

cos²θ + cos²(90°-θ)

= cos²θ + sin²θ [cos(90°-θ)=sinθ]

= 1

Answer 2

$\textbf{ Question}$

Find the value of cos²θ+ cos²(90-θ)

$\textbf{ Solution}$

$cos ^{2} \theta + {cos}^{2} (90 - \theta)$
As we know that —

$cos(90 - \theta) = sin \theta$

$cos ^{2} \theta + {cos}^{2} (90 - \theta) \\ \\ cos ^{2} \theta + {sin}^{2}\theta$

From 1st Identity

$sin^{2}\theta + cos^{2}\theta = 1$

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$\huge\bold{ Thanks}$