Points to Remember
• In a parallelogram the opposite sides and opposite angles are equal
• The diagonals of a parallelogram bisect each other.
• The diagonals of a parallelogram divides it into two congruent triangles
• A quadrilateral is a parallelogram if its opposite sides are equal .
• Parallelogram on the same base and between same parallel are equal in area.
• Triangles on the same base and between same parallel are equal in area.
• Parallelogram is a rhombus if its diagonals are perpendicular.
• There is one and only one circle passing through three non-collinear points.
• Equal chords of a circle subtend equal angles at the centre.
• Perpendicular from the centre of a circle to a chord bisects the chord.
• Equal chords of a circle are equidistant from the centre.
• The angle substended by an arc of a circle at the centre is double the angle subtended by it at any point on the remaining part of the circle.
• The angle in a semi circle is a right angle.
• Angles in the same segment of a circle are equal.
• The sum of either pair of opposite angle of a cyclic quadrilateral is 180o.
• If one side of a cyclic quadrilateral is produced then the exterior angle is equal to the interior opposite angle.