Question

Please help with the problem attached.

Answer 1

Answer:

Step-by-step explanation:

You have to use the Law of Cosines here to find angle R.  Namely,

$r^2=q^2+s^2-2qscosR$

Filling in:

$99^2=54^2+141^2-2(54)(141)cosR$ and

$9801=2916+19881-15228cosR$ and

$9801=22797-15228cosR$ and

$-12996=-15228cosR$ so

$.853427896=cosR$

Use the 2nd button and then the cos button to find the angle that has a cos of that decimal.  You should get, as long as you are in degree mode, that angle R = 31.4°