In the diagram, POS and ROT are straight lines, OPQR is a parallelogram. |OS| = |OT| and ∠OST = 50°. Calculate ∠OPQ.
A.
160o
B.
140o
C.
120o
D.
100o
Correct answer is D
< T = < S = 50° (OS = OT)
< SOT = 180° - 2(50°) = 80°
< ROP = 80° (vertically opposite angle)
\(\therefore\) < OPQ = 180° - 80° = 100° (adjacent angles)