You can use pre-calculus to calculate the intersection without a calculator:
lowest value of
(since the intersections occur when both functions have the same values)
Divide both sides by cos(x):
You should remember from your precalc days that this is equal to .
Now, some calc I formulas to calculate the volume...
The y-axis is the line x=0.
R is the distance from the elemental strip to the axis of rotation, which in the case of the y-axis, is simply x.
H is the height of the elemental strip, which is the higher function minus the lower function. You know the cosine functions starts at 1, which is higher than the sine function.
which I'm sure you can evaluate using integration by parts.
Hope I helped