29
Aug
Theorem 10.10: If a line segment joining two points subtends equal angles at two other points lying on the same side of the line containing the line segment, the four points lie on a circle (i.e. they are concyclic).
Prerequisite
Any four points in a plane are concyclic if these lie on a circle. The quadrilateral formed by joining all these points is called a cyclic quadrilateral. The prerequisite to prove the above mentioned theorem is theorem 10.5 which states that there always exists one (and only one) circle passing through three non-collinear points. It is highly recommended that you should watch the prerequisite theorem first in case you are not aware of this.
Here is the direct link to YouTube video tutorial of theorem 10.5.
Chapter 10 – Circles
