Calculating a conditional expectation (probability theory)

Question

Let $X$ and $Y$ be two random variables with the joint probability density function $f_{xy}(x,y)=(15/4) x y^2$ for $0 < 2 y \leq x \leq 2$ and $0$ otherwise.

Calculate ${\cal E}[X^2+Y^2 \leq 1 | X \geq 0.5]$