Not understanding this precalculus problem, please help!?

The three sides of a triangle are 14, 17 and 27. Correct to the nearest tenth of a degree, what is the measure of the angle opposite to the largest side?

A) 91.7o

B) 92.3o

C) 96.0o

D) 100.5o

E) 102.0o

F) 108.1o

G) 108.5o

H) 120.8o

I) none of these

2 Answers

Relevance
  • 8 years ago

    Law of Cosines. Let X = the angle. Then:

    27^2 = 14^2 +17^2 - 2*14*17*cosx

    Now solve for x

  • 8 years ago

    27² = 14² + 17² - 2*14*17cosΘ

    cosΘ = (14² + 17² - 27²)/(2*14*17)

    cosΘ = -.5126

    Θ = 120.8º

    answer choice is H)

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