In the diagram, PTR is a tangent to the centre O. If angles TON =
MATHEMATICS
WAEC 2015
In the diagram, PTR is a tangent to the centre O. If angles TON = 108°, Calculate the size of angle PTN
- A. 132°
- B. 126°
- C. 108°
- D. 102°
Correct Answer: B. 126°
Explanation
In the diagram; 108° + x + x = 180° (sum of angle in a triangle)
108° + 2x = 180°
x = 180° - 108°
= 72°
x = \(\frac{72^o}{2}\)
= 36°
(Angle between tangent and a chord through the point of contact)
Hence, angle PTN = 90 + 36
= 126°
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