A quadrilateral, in general, is not a parallelogram.
If it is a parallelogram then you will have some additional information about its sides and angles. If you do not have such information it is not possible to prove that it is a parallelogram.
Draw a diagonal which will divide the quadrilateral into two triangles and use the additional information that you have to show that the triangles are congruent. This can then be used to show equality of sides or of angles: the latter can then be used to show that sides are parallel.
Note that the choice of which diagonal may influence how (if at all) you proceed.
showing consecutive angles are congruent
The side of a triangle or parallelogram used to help find area is called the base. Area is base times height in a parallelogram. In a triangle, it is 1/2 times base times height.
-- quadrilateral -- parallelogram
A quadrilateral is a generic term used to describe a four sided polygon. In other words, it is a shape that has four sides.A rectangle, rhombus, parallelogram and trapezium (trapezoid) has four sides. In light of this, it can be classified as a quadrilateral but, if the quadrilateral has no sides and angles equal, it could not be classified as any of the foregoing.
It is the base.
showing consecutive angles are congruent
The side of a triangle or parallelogram used to help find area is called the base. Area is base times height in a parallelogram. In a triangle, it is 1/2 times base times height.
-- quadrilateral -- parallelogram
A quadrilateral is a generic term used to describe a four sided polygon. In other words, it is a shape that has four sides.A rectangle, rhombus, parallelogram and trapezium (trapezoid) has four sides. In light of this, it can be classified as a quadrilateral but, if the quadrilateral has no sides and angles equal, it could not be classified as any of the foregoing.
Its base.
Its base.
It is the base.
I equally quadrisected a candy bar for my three friends and myself.
It is usually called the "base".
SAS
A regular triangle, quadrilateral (i.e., square) and hexagon may be used.
a rectangle is no more than a parallelogram with 90 degree angles, or you could call it simply a quadrilateral