Question

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

• A. \N
• B. $\sqrt{2}$
• C. 1
• D. 2

Answer 1

The correct option is C 1

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