posted by bob on .
each of three circles touches the other 2.circle A has a radius of 8 cm. circle B has a radius of 4 cm.circle C has a radius of 1 cm.a triangle is formed by connecting the centers of the 3 triangles. determine the largest angle for the triangle and in which circle is the largest angle?
Draw a diagram. The sides of the triangle are 12,9,5
The angle at C subtends the longest side, so it will be the largest angle.
by the law of cosines,
12^2 = 9^2 + 5^2 - 2*9*5 cosC
144 = 81 + 25 - 90 cosC
cosC = -38/90
C = 115°