Answer: 82 degrees
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Explanation:
Apply the law of cosines to find angle C
c^2 = a^2 + b^2 - 2*a*b*cos(C)
19^2 = 11^2 + 17^2 - 2*11*17*cos(C)
361 = 121 + 289 - 374*cos(C)
361 = 410 - 374*cos(C)
361 - 410 = -374*cos(C)
-49 = -374*cos(C)
-374*cos(C) = -49
cos(C) = (-49)/(-374)
cos(C) = 0.131016042780749 ..... which is approximate
C = arccos(0.131016042780749)
C = 82.4716905247836
C = 82 degrees
Notes:
- arccos is shorthand for "arccosine". It is the same as inverse sine.
- Make sure your calculator is in degree mode. You can check by computing cos(60) and you should get 0.5
