**Definition: **A parallelogram is a quadrilateral with parallel opposite sides. Rectangles, rhombi and squares are all parallelograms.

A parallelogram has the following properties:

– Opposite sides are congruent and parallel

– Opposite angles are congruent

– Diagonals bisect each other

– Consecutive angles are supplementary

**Example: **Find the lengths of side BC and side DC

**Solution:**

Use the given information to determine the side lengths of sides BA and AD.

Step 1: The figure indicates that this quadrilateral has two pairs of parallel lines, so we can conclude that it is a parallelogram

Step 2: Since parallelograms have two pairs of congruent sides, we know side BA is congruent to side CD,

and side BC is congruent to side AD.

Step 3: Since side AB = 5 mm, then CD must also have a length of 5 mm

Since side AD = 3 + 4 = 7 mm, then side BC must also equal 7mm.

Based on the properties of a parallelogram, we can conclude that side BC = 7mm, side DC = 5mm.

Still need help identifying parallelograms? Download Yup and get help from an expert math tutor 24/7.