Question

If $\sin \theta +{\sin }^2\theta =1$ then the value of $({\cos }^2\theta +{\cos }^4\theta )$ is

• A. 0
• B. 1
• C. 2
• D. 3

Answer 1

The correct option is B 1

As given

$sin\theta +si{n}^2\theta =1$

$\Rightarrow sin\theta =1-si{n}^2\theta$

$\because 1-si{n}^2\theta =co{s}^{2}A$

$\therefore sin\theta =co{s}^2\theta$......1

Then $co{s}^2\theta +co{s}^4\theta$

$\Rightarrow co{s}^2\theta +(co{s}^2\theta {)}^2$

From 1

$\Rightarrow sin\theta +si{n}^2\theta \Rightarrow 1$