10. (10 Points) Evallate the line interal along the curve C : r(t) = (t²+1)i+ (t² - 1)j, 0 ≤ t ≤ 2. Hint you may find a potential function f of the vector field F(x,y) = find f so that F = ∇f.

9.(10 Poins) Evaluate the triple integral , where E is the solid region in bounded by the surface z = 1 and z = x²+y².

8. (10 Points) Evaluate the double integral , sin(x+y)dA where D is the regsion bounded by x+y= π, x+y = 0 and x -y =π and x-y=0.