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P is the centre of a circle that passes through O, and O is the center of a circle that passes through P. If C = 66 degrees, then the measure of OPB is?
Please find the diagram in the link below:
https://ibb.co/1XKHRrr
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The solution in the post by @math_tutor_2020 is incorrect.
I came to bring a correct solution.
Triangle PCB is is isosceles triangle. Therefore, angle PBC = angle PCB = 66°.
Hence, angle BPC is 180° - 66° - 66° = 48°.
Let x be the measure of the angle A.
Triangle APO is isosceles triangle, so angle APO = x.
Angle POB is an exterior angle of the triangle APO; therefore, angle POB = x+x = 2x.
Triangle POB is isosceles triangle; therefore, angle PBO = angle POB = 2x.
Write the sum of interior angles of triangle POB
angle POB + angle PBO + angle OPB = 180°,
or
2x + 2x + angle OPB = 180°.
It implies angle OPB = 180° - 4x.
Next, write the sum of angles APO, OPB and BPC
x + (180° - 4x) + 48° = 180°.
From this equation,
48° = 3x,
x = 48°/3 = 16°.
ANSWER. The measure of the angle OPB is 180° - 4x = 180° - 4*16° = 180° - 64° = 116°.
Solved.