12. Set up, but do not evaluate, the following integrals :
(a) \iint_R f(x,y)dA where R is the triangular region with vertices at (0,0), (0,2) and (2,2).
(b) \iint_R f(x,y)dA where R is the polar region bounded by \(\theta = 0, \theta = \frac{\pi}{4}\) and r=0, r=3. Use polar co-ordinates.
(c) \iiint_E f(x,y,z)dV where E is the solid region bounded below by
z = x^2 + y^2 and above by the hemisphere z = \sqrt{2 - x^2 - y^2}.
