In the diagram, PR is a diameter of the circle PQRS. PST ...
In the diagram, PR is a diameter of the circle PQRS. PST and QRT are straight lines. Find QRS
A.
20o
B.
25o
C.
30o
D.
35o
Correct answer is B
< PSR = 12(180o) = 90o (angle substended by a semi-circle)
∴ < TSR = 90o
< SRT = 90o - 30o = 60o
< PRS = 90o - 35o = 55o
< PRQ = 180 - (60o + 55o) = 180 - 115o = 65o
< SQR = 35o(angles in the same segment)
< QSR + < SRQ + < SQR = 180o
< QSR + 120o + 35o = 180o
< QSR + 155 = 180o
< QSR = 180o - 155o
= 25o