A circle C1 of radius 5 has its center at the origin. Outside this circle is a first quadrant circle C2 of radius 2 that is tangent to C1. The y coordinate of the center of C2 is 3. Find the x coordinate of the center of C2.

Answer 1

Draw it !
length of line between centers = 5+2 = 7 (hypotenuse)
height of triangle =3
x^2 + 3^2 = 7^2
x^2 = 49 - 9 = 40
x = 2 sqrt 10