Answer : 29.5°
Given r = 10, q = 20, and Q = 100°
From the attached figure we can see that two sides and one angle is given
We use sine rule to find angle R

In triangle QRS

r = 10, q = 20, and Q = 100°

Replace all the values


=sin R
0.4932403876 = sin (R)
R=

R= 29.5 degrees