Circles

RD Sharma new

• use pythagoras theorem, whenever 2 sides are given ad third side is being asked, with respect to the tangent to the circle
• draw teh diagram and mark all the measurements given first
• angle in the semicircle maed by the diameter is 90 degree
• property of cyclic quadrilateral - sum of opposite sides are equal
• tangents drawn from any point on the common chord of 2 intersecting circles are equal
• let AM be the tangent from an external point A and a chord to the circle through A intersecting the circle at points X and Y, then AM^2 = AX * AY
• angle subtended by the arc at the centre is double the angle subtended by it at the remaining part of the circle