SOLUTION: This problem refers to triangle ABC. If a = 15 yd, b = 16 yd, and c = 17 yd, find the largest angle. (Round your answer to the nearest whole number.) = °

Algebra ->  Triangles -> SOLUTION: This problem refers to triangle ABC. If a = 15 yd, b = 16 yd, and c = 17 yd, find the largest angle. (Round your answer to the nearest whole number.) = °      Log On


   



Question 1136157: This problem refers to triangle ABC.
If a = 15 yd, b = 16 yd, and c = 17 yd, find the largest angle. (Round your answer to the nearest whole number.)

= °

Answer by MathLover1(20850) About Me  (Show Source):
You can put this solution on YOUR website!

If a+=+15 yd, b+=+16+yd, and c+=+17+yd, find the largest angle.
The largest angle occurs opposite the largest side, so it is angle C.
use Law of Cosines:
c%5E2+=+a%5E2+%2B+b%5E2+-2ab+%2Acos%28+C%29...plug in given data
17%5E2+=+15%5E2+%2B+16%5E2+-2%2A15%2A16+%2Acos%28+C%29
289+=+225+%2B+256+-480+%2Acos%28+C%29
289+-225+-+256+=-480+%2Acos%28+C%29
-192+=-480+%2Acos%28+C%29
480+%2Acos%28+C%29=192
cos%28+C%29=192%2F480
cos%28+C%29=0.4
+C=cos%5E-1%280.4%29
+C=66.42°
+C=66°