Question

$x=2{\sin }^2\theta ,y=2{\cos }^2\theta +1$, find the value of $x+y$

Answer 1

$\begin{array}{cc}x=2{\sin }^2\theta ,y=2{\cos }^2\theta +1& \\ x+y=2{\sin }^2\theta +2{\cos }^2\theta +1& \\ 2\left[{\sin }^2\theta +{\cos }^2\theta \right]+1& \left[{\sin }^2\theta +{\cos }^2\theta =1\right]\\ 2+1=3.& \end{array}$