Posted by dell on .
Two cars leave the same point at noon. One car travels North and the other car travels East. Suppose the North bound car is travling 40mph and after two hours, the two cars are 100 miles apart. How fast is the other car going?

math 
Reiny,
Your diagram should be a rightangled triangle with sides 80, 2r, and hypotenuse 100
(2r)^2 + 80^2 = 100^2
4r^2 = 3600
r^2 = 900
r = √900 = 30
The other car was going 30 mph