Posted by **Chris** on Sunday, February 17, 2013 at 9:36pm.

Three circles with radii of 4, 5, and 6 cm, respectively, are tangent to each other externally. Find the angles of the triangle whose vertexes are the centers of the circles.

- Trig -
**bobpursley**, Sunday, February 17, 2013 at 9:40pm
sides of triangle are (2+2.5),(2+3),(2.5+3)

Start with law of cosines

c^2=a^2+b^2-2abCosC

label the sides a,b, c solve for angle C

Then, use the law of sines

a/SinA=c/SinC solve for angle A

then use the fact that the sum of the angles is 180 deg, find angle B.

check angle B with the law of sines.

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