Two spherical balls lie on the ground touching. If one of the balls has a radius of 10 cm, and the point of contact is 12 cm above the ground, what is the radius of the other ball (in centimeters)?	Choose the correct answer.
A) 14	B) 15	C) 16	D) 18	E) 20
A straight line will join the two centers and the point of contact, thus making similar triangles.   2/10 = (r-12)/r   2r = 10r - 120   r = 15   The answer is 15.
<result>B</result>
Two spherical balls lie on the ground touching. If one of the balls has a radius of 10 cm, and the point of contact is 12 cm above the ground, what is the radius of the other ball (in centimeters)?