This is the concept of geometry, we are required to find the measure of the base angles given that triangle STQ is an isosceles triangle. To solve this we proceed as follows;
The base angle of am isosceles triangle are equal. Let the angles be x, thus;
x+x+48=180 (sum of angles in a triangle add up to 180°)
2x+48=180
putting like terms together we get:
2x=180-48
2x=132
dividing both sides by 2 we get;
(2x)/2=132/2
x=66°
The base angles measure 66°;
also;
∠STR=∠QTR=48/2=24°