How many two person can be picked out of a group of 7

Answer the questions in the attachment. a rescue helicopter is at point a and a rescue boat is at point e. the helicopter pilot spots boats in distress at points d and c,with angles as marked in the diagram. figure abce is a rectangle. the altitude of the rescue helicopter, represented by ae, is 5000 feet.

Can somebody 1. what is the formula for finding the vertical distance between two points on a coordinate plane?

The radius of the earth is two times the radius of the moon. what fraction of the volume of the earth is the volume of the moon?