Plotting the diagram of {x}^{2}+{y}^{2}\leq 21&{y}^{2}\leq 4x for x≥1 we get,

Now from above diagram required Area Δ=2∫132xdx+2∫32121−x2dx
⇒Δ=38(33−1)+21sin−1(72)−63
So, 21(Δ−21sin−1(72))
=21(38(33−1)+21sin−1(72)−63−21sin−1(72))
=21(38(33−1)−63)
=223−38
=3−34