Question 91

If $$sin θ + sin^{2} θ = 1$$ then $$cos^2 θ + cos^4 θ$$ is equal to

Solution

Expression : $$sin\theta + sin^2\theta = 1$$

=> $$sin\theta = 1 - sin^2\theta$$

=> $$sin\theta = cos^2\theta$$

To find : $$cos^2\theta + cos^4\theta$$

= $$cos^2\theta + (cos^2\theta)^2$$

= $$cos^2\theta + sin^2\theta$$

= 1

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