Answer:
Step-by-step explanation:
1. Quadrilateral. A quadrilateral can be convex or concave. Here only convex quadrilaterals are considered. Its properties are
(a) The four sides are unequal.
(b) Sum of the interior angles = 4 right angles or 360 degrees.
(c) The two diagonals intersect.
(d) The line joining the mid-points of any two adjacent sides is parallel to the corresponding diagonal and equal to half of it.
(e) Lines joining the mid points of the sides of a quadrilateral in an order form a parallelogram.
(f) The sum of the four exterior angles is 4 right angles.
(g) The sum of the four interior angles is 4 right angles.
