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Theorem : The Angle in a Semi-Circle is a Right Angle

Theorem: The angle in a semicircle is a right angle

Given : A circle with centre 0 with  ∠A0B at centre and  ∠ACB at the circumference of the circle .
RT.P. : the angle in a semicircle is a right angle. ie : ACB= 90o

1   AOB = 2ACB  ||  angle at the centre is twice the angle at the circumference  of a circle.
2 . ACB = ½AOB  ||  by statement 1
3 . ACB =½ x 180o  || As  AOB = 180o
4. &there4 ∠ACB = 90o  Proved

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