Question

Which of the following applies the law of cosines correctly and could be solved to find m∠E? ANSWERS: A) cos E = 312 + 392 – 2(31)(39) B) C) 562 = 392 – 2(39) ⋅ cos E D) 562 = 312 + 392 – 2(31)(39) ⋅ cos E

Answer 1

This question is incomplete because the options were not properly written.

Complete Question

Which of the following applies the law of cosines correctly and could be solved to find m∠E? ANSWERS:

A) cos E = 31²+ 39² – 2(31)(39)

C) 56² = 39² – 2(39) ⋅ cos E

D) 56² = 31² + 39² – 2(31)(39) ⋅ cos E

Answer:

D) 56² = 31² + 39² – 2(31)(39) ⋅ cos E

Step-by-step explanation:

From the above diagram, we see are told to apply the law of cosines to solve for m∠E i.e Angle E

The formula for the Law of Cosines is given as:

c² = a² + b² − 2ab cos(C)

Because we have sides d , e and f and we are the look for m∠E the law of cosines would be:

e² = d² + f² - 2df cos (E)

e = 56

d = 39

f = 31

56² = 39² + 31² - (2 × 39 × 31) × cos E

Therefore, from the above calculation and step by step calculation, the option that applies the law of cosines correctly and could be solved to find m∠E

Is option D: 56² = 31² + 39² – 2(31)(39) ⋅ cos E