Question

If $\sin \theta +{\sin }^2\theta =1,$ then ${\cos }^2\theta +{\cos }^4\theta =$

• A. $\sqrt{2}$
• B. 1
• C. 2
• D. 0

Answer 1

The correct option is B 1

Given that $\sin \theta =1-{\sin }^2\theta \Rightarrow \sin \theta ={\cos }^2\theta .$ $\therefore {\cos }^2\theta +{\cos }^4\theta =\sin \theta +{\sin }^2\theta =1$