If ${\sec }^4\theta +{\sec }^2\theta =10+{\tan }^4\theta +{\tan }^2\theta$ then ${\sin }^2\theta =$

$\begin{array}{c}{\sec }^2\theta ({\sec }^2\theta +1)=10+{\tan }^2\theta ({\tan }^2\theta +1)\\ {\sec }^2\theta ({\sec }^2\theta +1)=10+{\tan }^2\theta .{\sec }^2\theta \\ {\sec }^2\theta (1+{\sec }^2\theta -{\tan }^2\theta )=10\\ {\sec }^2\theta (1+1)=10\\ {\sec }^2\theta =5\\ {\cos }^2\theta =\frac{1}{5}\end{array}$

$\begin{array}{c}\Rightarrow 1-{\sin }^2\theta =\frac{1}{5}\\ \Rightarrow {\sin }^2\theta =\frac{4}{5}\end{array}$