A man is flying in a hot-air balloon in a straight line while keeping it at a constant altitude. As he approaches a parking lot
and notices that the angle of depression from his balloon to a friend's car is 36º. He flew directly over the car. A minute and a half later he had travelled 360 feet horizontally; he looks back to see his friend getting into the car and observes the angle of depression to be 37º. At that time, what is the distance between him and his friend?
The easiest way to do this is to set up a proportion. 6/12=x/10. To solve, cross-multiply and divide. Multiply 6 and 10 (6*10=60) and divide by 12 (60/12=5).
You can also find that 6/12 is equal to 1/2 by dividing each side by 6. Then multiply 10 by 1/2 (or divide 10 by 2) to get the final answer of 5 people.