Calculus volume question, can anyone solve it (using the disc method, shell method and/or washer method)?

Question

Consider the area enclosed by y = tan x , y=1, and x=0. Find the volume of the solid generated when the region is rotated about:
a) the x axis
b) the line y = 1
the answers should be but may not be a) 1.793 b).964

Answer 1

a) y= 1 corresponds to x= pi/4
So this is the Int ofpi*y^2dx between 0 and pi/4= (disc method)
=pi*Int tan^2x dx
If you put tan x = u
(1+tan^2x)dx=du so dx = du/(1+u^2)
so the integral becomes
pi Int u^2/(1+u^2) between 0 and 1=
=pi* (u-Arctan u) =pi(1-pi/4)=0.6742
The second is piInt(1-y)^2dx between 0and
pi/4