For questions 8, 9, 10: Note that a + y = 12 is the equation of a circle of radius 1. Solving for y we have y = v1 - a2, when y is positive. 8. Compute the length of the curve y = V1 - 12 between x = 0 and x = 1 (part of a circle.) 9. Compute the surface of revolution of y = V1 - x2 around the x-axis between x = 0 and x = 1 (part of a sphere.)