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 is D
< Q = < R (OQ = OR = radii)
< QOR = 180° - 2(40°) = 100°
< QSR = < RPQ = \(\frac{1}{2}\) < QOR
= \(\frac{100}{2} = 50°\)