Answer:
Step-by-step explanation:
All the vertices of triangle are equal distant from circum center.
RC = PC = QC
RC = PC
5x - 15 = 3x + 7
Add 15 to both sides
5x = 3x + 7 + 15
5x = 3x + 22
Subtract 2x from both sides
5x- 3x = 22
2x = 22
Divide both sides by 2
x = 22/2
x = 11
QC = 51 - x
= 51 - 11
QC = 40
