The value of cos² 29° + cos² 61° is:

Correct option is C

Sol.

Given:

cos² 29° + cos² 61°

Formula Used:

$$\sin^2(\theta) + \cos^2(\theta) = 1 \\\cos(90^\circ - \theta) = \sin(\theta)\\$$

Solution:

$$\cos^2(29^\circ) + \cos^2(61^\circ)\\\cos^2(29^\circ) + \sin^2(90^\circ - 61^\circ)\\\cos^2(29^\circ) + \sin^2(29^\circ)\\= 1 ( \sin^2(\theta) + \cos^2(\theta) = 1)\\$$

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