A quadrilateral has 4 sides and ______ vertices (corners).
A quadrilateral has _______ corner or vertices.
Fill in the blanks : (i) A quadrilateral has ___ sides. (ii) A quadrilateral has ___ angles. (iii) A quadrilateral has ___ vertices, no three of which are ___. (iv) A quadrilateral has ___ diagonals. (v) A diagonal of a quadrilateral is a line segment that joins two ___ vertices of the quadrilateral. (vi) The sum of the angles of a quadrilateral is ___.
A quadrilateral has vertices (4, 1), (1, 7), (-6, 0) and (-1, -9). Show that the mid-points of the sides of this quadrilateral form a parallelogram.