PLEASE HELP I NEED THIS DONE IN LESS THAN AN HOUR!?

Find the volume of the solid whose base is the circle x^2+y^2=81 and the cross sections perpendicular to the x-axis are triangles whose height and base are equal.

Find the area of the vertical cross section A at the level x=2

A=

V=

2)Find the volume of the solid whose base is the semicircle y=\sqrt{16-x^2} where -4\le x\le 4, and the cross sections perpendicular to the x-axis are squares.

3)Find the volume of the solid whose base is the region |x| + |y| \le 5 and whose vertical cross sections perpendicular to the y-axis are semicircles (with diameter along the base).

4)Let V be the volume of a pyramid of height 10 whose base is a square of side 8.

A=

V=