In the diagram, PQRS is a circle center O. PQR is a diameter and ∠PRQ = 40°. Calculate ∠QSR.
-
A.
30o -
B.
40o -
C.
45o -
D.
50o
Correct Answer: Option D
Explanation
< Q = < R (OQ = OR = radii)
< QOR = 180° – 2(40°) = 100°
< QSR = < RPQ = (frac{1}{2}) < QOR
= (frac{100}{2} = 50°)