Angle in a semicircle is a right angle - Part 2

  1. Chapter 10 Class 9 Circles (Term 2)
  2. Serial order wise


Theorem : Angle subtended by a diameter/semicircle on any point of circle is 90 right angle Given : A circle with centre at 0. PQ is the diameter of circle subtending PAQ at point A on circle. To Prove : PAQ = 90 Proof : Now, POQ is a straight line passing through center O. Angle subtended by arc PQ at O is POQ = 180 Also, By theorem 10.8 : The angle subtended by an arc at the centre is double the angle subtended by it at any point on the remaining part of the circle. Thus, POQ = 2 PAQ POQ/2 = PAQ 180 = PAQ 90 = PAQ PAQ = 90 Hence, Proved.

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Davneet Singh
Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 10 years. He provides courses for Maths and Science at Teachoo.