Answer:
Step-by-step explanation:
You have to use the Law of Cosines here to find angle R. Namely,
[tex]r^2=q^2+s^2-2qscosR[/tex]
Filling in:
[tex]99^2=54^2+141^2-2(54)(141)cosR[/tex] and
[tex]9801=2916+19881-15228cosR[/tex] and
[tex]9801=22797-15228cosR[/tex] and
[tex]-12996=-15228cosR[/tex] so
[tex].853427896=cosR[/tex]
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°
