For this solid, each cross section perpendicular to the x-axis are isosceles right triangles with one leg in . Which of the following integrals gives the volume of this solid?
1) ∫(0 to 1) √(1 - x²) dx
2) ∫(0 to 1) √(1 - x) dx
3) ∫(0 to 1) √(1 - x³) dx
4) ∫(0 to 1) √(1 - x⁴) dx