PLEASE HELP A circus acrobat jumps off a raised platform. He lands on a trampoline at stage level below. His path can be modeled by the relation h=-0.5d^2+0.5d+6, where h is his height above the stage and d is his horizontal distance from the edge of the platform, both in meters.

a) What is the height of his platform?
b) How far from the edge of the platform did the acrobat land?
c)What was the acrobat's maximum height above the stage?