the diagram shows a circle,centre O.the lines AB,BC and CA touch the circle at P,Q and R respectively. explain CQO=90 degrees
The three lines AB,BC,CA are all tangent lines to the circle, and the circle is an inscriberd circle of the triangle ABC.
A tangent to a circle will touch it at one point only.
The tangent BC will touch the circle at the point Q.
O is the centre point of the circle.
OQ is a radius of the circle.
The radius of a circle to a point on the circle will always be perpindicular to the tangent at that point.
Hence, the radius OQ is perpindicular to the tangent BC.
i.e. the angle OQC is 90º