NEED HELP with my question

Aman steps out of a plane at a height of 4,000m above the ground falls 2,000m very quickly and then opens his parachute and slowly falls the remaining 2000m to the ground what height above the ground would be the best choice for a reference point

The lengths of the two sides of a right triangle are 5 inches and 8 inches what is the difference the possible lengths of the third side of the triangle

An airplane can ascend at a rate of 52 1/2 meters in 1/3 of a second. how many meters can the airplane ascend in one second?