In the diagram, PQR is a triangle.|PQ| = |PR|, |PS| = |SQ| and PRS = 50^\circ. What is the size of ∠PSQ?
Attached Figure / Diagram
A
75o
B
80o
C
85o
D
95o
Verified Correct Answer: B.
Step-by-Step Mathematical Solution
< PQS = 50^\circ (PQ = PR)
< PQS = < SPQ = 50^\circ (QS = PS)
In triangle PSQ, < PQS + < QPS + < PSQ = 180^\circ
50^\circ + 50^\circ + < PSQ = 180^\circ
< PSQ = 180^\circ - 100^\circ = 80^\circ
Source: Myschool Past Questions Archive (Record #26508)