If \(\cos (x)+\cos ^2(x)=1\), then \(\sin ^2(x)+\sin ^4(x)\) is equal to

If \(\cos (x)+\cos ^2(x)=1\), then \(\sin ^2(x)+\sin ^4(x)\) is equal to
  1. 0
  2. 1
  3. -1
  4. 2

Solution

It is given that, \(\begin{aligned} \cos x+\cos ^2 x & =1 \Rightarrow \cos x=\sin ^2 x \\ \therefore \quad \sin ^2 x+\sin ^4 x & =\cos x+\cos ^2 x=1 \end{aligned}\) Hence, option (b) is correct.

Asked in: AP EAMCET 2020 (21 Sep Shift 2)

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