Question

In angle DEF, d=13.5 cm, e=18.2 cm and F = 60 degrees
Determine the measure of f to the nearest tenth of a centimetre.

I know the answer is 16.4 cm but how do I get it

Answer 1

clear case of the cosine law.

You must have studied this in class or else how could they expect you to do it ?

f^2 = 13.5^2 + 18.2^2 - 2(13.5)(18.2)cos(60 degrees)
= .....

Answer 2

Thank you!! :)