8.6 SUMMARY:
In this chapter, you have studied the following points :
1. Sum of the angles of a quadrilateral is 360°
2. A diagonal of a parallelogram divides it into two congruent triangles.
3. In a parallelogram:
(i) opposite sides are equal
(ii) opposite angles are equal
(iii) diagonals bisect each other
4. A quadrilateral is a parallelogram, if :
(i) opposite sides are equal or
(ii) opposite angles are equal or
(iii) diagonals bisect each other or
(iv)a pair of opposite sides is equal and parallel
5. Diagonals of a rectangle bisect each other and are equal and vice-versa.
6. Diagonals of a rhombus bisect each other at right angles and vice-versa.
7. Diagonals of a square bisect each other at right angles and are equal, and vice-versa.
8. The line-segment joining the mid-points of any two sides of a triangle is parallel to the third side and is half of it.
9. A line through the mid-point of a side of a triangle parallel to another side bisects the third side.
9. The quadrilateral formed by joining the mid-points of the sides of a quadrilateral, in order, is a parallelogram.