Target shooting disks are launched into the air from a machine placed at some height above the ground. The height, h in metres, of the disk after launch is modelled by the function h=−3(-1)2+15 where t is time in seconds. a.) When does the shooting disk reach its maximum height? What is the maximum height reached by the disk? Explain how you determined the answers.

b.) From what height above the ground was the disk launched?

c.) What is the height of the disk 3 seconds after it was launched?