I need help can you guys help me?

The diameter of a table is 5 feet. what is the circumference

Astuntman jumping off a 20-m-high building is modeled by the equation h=20-5t^2, where t is the same in seconds. a high-speed camera is ready to film him between 15m and 10m above the ground. for which interval of time should the camera film him?

Find the missing factor. write your answer inexponential form.9^2=9^4×