1. The base of a certain solid is an equilateral triangle of side s with one vertex at the origin and an altitude along the X-axis. Each plane section perpendicular to the X-axis is a square. Find the volume of the solid.

2. The base of a solid is the circle is x^2+y^2=a^2. Each plan section perpendicular to the y-axis is an isosceles right triangle with one leg in the base of the solid. Find the volume.

3. The base of a solid is the region between the x-axis and the curve y=sinx between x=0 to x= pi/2. Each plane section perpendicular to the x-axis is an equilateral triangle with one side in the base of the solid. Find the volume.

I am totally lost in these problems.