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# In the diagram, PTR is a tangent to the centre O. If angles TON = 180o, Calculat...

### Question

In the diagram, PTR is a tangent to the centre O. If angles TON = 180o, Calculate the size of angle PTN.

A) 132o

B) 126o

C) 108o

D) 102o

### Explanation:

In the diagram; 180o + x + x = 180o(sum of angle in a $$\\bigtriangleup) 180o + x = 180v x = 180o - 108o = 72o x = \(\frac{72^o}{2}$$

= 36o

(Angle between tangent and a chond through the point of contact)
Hence, angle PTN = 90 + 36

= 126o

## Dicussion (1)

• In the diagram; 180o + x + x = 180o(sum of angle in a $$\\bigtriangleup) 180o + x = 180v x = 180o - 108o = 72o x = \(\frac{72^o}{2}$$

= 36o

(Angle between tangent and a chond through the point of contact)
Hence, angle PTN = 90 + 36

= 126o