solid of revolution and a matrix q

Hi guys, not sure if anyone can help me but i'm super stuck with two uestions for my up coming exam:

Find the volume of the solid of revolution obtained by rotating, a full turn about the

x-axis, the area between the x-axis and the curve y = 2 sin x, for x

∈ [π/4, 3π/4].

and this one too

Matrices A, B, C , D & X satisfy equation A(X + B)C = D, and D is a 5×5 matrix. If A has 3 columns, and C 4 rows, ﬁnd the dimensions of each matrix. Give conditions on the matrices A, B, C & D, if necessary, to ensure that we can solve the above equation. Find an expression for the unknown matrix X .

Thanks very much