In the figure, PQ and QR are chords of the circle PQR. QRS is a straight line and PR is equal to RS, < PSR is 20o. What is the size of
Attached Figure / Diagram
A
70o
B
90o
C
80o
D
40o
E
60o
Verified Correct Answer: C.
Step-by-Step Mathematical Solution
Isosceles Triangle PSR:
RSP ≡ RPS → 20º
That is PRQ = 40º
POQ = 2 * 40 = 80º (Angle subtended by chord PQ at centre is twice angle subtended at circumference).
The size of POQ = 80º
Source: WAEC / JAMB / NECO Classroom Archive (Record #32736)