

ParallelogramsProperties, Shapes, Diagonals and Area A parallelogram is quadrilateral comprised of two pairs of parallel lines. There are several rules involving
Interactive Parallelogram(see full size )The full size interactive parallelogram has additional features such as the lengths of the diagonals.
Angles of A ParallelogramOpposite Angles are Congruent
Triangles can be used to prove this rule about the opposite angle. Consecutive angles are supplementary.
What is the measure of angles A, B and C in parallelogram ABCD?
What is the measure of x, y, z in parallelogram below?
In a parallelogram one of the angles measures 25°, what are the measures of the other angles?
one = 25° (this is the opposite angle) another = 18025 = 155° (a consecutive angle) a third = 18025 = 155°; (a consecutive angle) Sides of a ParallelogramThe opposite sides of a parallelogram are congruent. Triangles can be used to prove this rule about the opposite sides.. To explore these rules governing the sides of a parallelogram use Math Warehouse's interactive parallelogram
What is the value of x and y in the parallelogram below?
Since opposite sides are congruent you can set up the following equations: 2x − 10 = x + 80 and solve for x x =903y − 4 = y + 20 and solve for y y = 12 Diagonals of a Parallelogram
What is x and Y?
Since the diagonals bisect each other, y = 16 and x = 22
What is x?
x + 40 = 2x + 18 40 = x +18 40 = x + 18 22 = x
Properties of parallelograms: Angles  Sides  Diagonals Interactive Parallelogram  top
Classify Quadrilateral as parallelogram (a classic activity: have the students construct a quadrilateral and its midpoints, then create an inscribed quadrilateral. Then ask the students to measure the angles, sides etc.. of inscribed shape and use the measurements to classify the shape(parallelogram). Types of Parallelograms: rectangle  rhombus  square  rectangle vs. square  comparison of properties of each type of parallogram  Criteria prove quadrilateral is a parallelogram 