In the diagram, POS and ROT are straight lines, OPQR is a parallelogram. |OS| = |OT| and ∠OST = 50°. Calculate ∠OPQ.
Attached Figure / Diagram
A
160o
B
140o
C
120o
D
100o
Verified Correct Answer: D.
Step-by-Step Mathematical Solution
< T = < S = 50^\circ (OS = OT)
< SOT = 180^\circ - 2(50^\circ) = 80^\circ
< ROP = 80^\circ (vertically opposite angle)
\(\therefore\) < OPQ = 180^\circ - 80^\circ = 100^\circ (adjacent angles)
Source: WAEC / JAMB / NECO Classroom Archive (Record #26449)