Question

Find the length of side a. Round to the nearest tenth.

A) 12


B) 378.4


C) 18.3


D) 19.5

Answer 1

D) 19.5

Explanation:

The law of cosines gives you the relation ...

a² = b² + c² - 2bc·cos(A)

Substituting the given values, you have ...

a² = 13² + 11² - 2·13·11·cos(108°) ≈ 378.379

a ≈ √378.379 ≈ 19.452 . . . . take the square root

a ≈ 19.5