Question

Can someone help me with this trigonometry question

Answer 1

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