3.10 Application of integrals

1.

(a) $4$(b) $${\frac{3\pi}{16}}$$

2.

(a) $${4\pi^2}$$(b) $${5\pi^2}$$

3.

(a) $6$(b) $${\frac{1}{6}}$$(c) $${\frac{3\pi}{2}}$$