Answer
$$(4-\pi) $$
Work Step by Step
We need to integrate the integral to compute the volume.
$$Volume = \pi \int_{0}^{1} r^2 \space dy \\=\pi \int_{0}^{1} \tan^2 (\dfrac{\pi y}{4}) \space dy \\= \int_{0}^{1} [-(\pi)+(\pi) \cdot \sec^2 (\dfrac{\pi y}{4})] \space dy \\= \pi[-y+(\dfrac{4}{\pi}) \times \tan (\dfrac{\pi}{4} )-(-0+0)] \\=(4-\pi) $$
