What can you tell about the mean of each distribution

What is the length of bc ? enter your answer in the box.bc =

Atriangle with all sides of equal length is a/an triangle. a. right b. scalene c. equilateral d. isosceles

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?