In the figure, PQRS is a circle. If chords QR and RS are equal, calculate the value of x
A.
80o
B.
60o
C.
45o
D.
40o
Correct answer is D
SRT is a straight line, where QRT = 120
SRQ = 180o - 120o = 60o - (angle on a straight line)
also angle QRS = 180o - 100o (angle on a straight line) . In angles where QR = SR and angle SRQ = 60o
x = 100 - 60 = 40o