Parallelograms

Part of the Polygons & Quadrilaterals section of Coddy's Geometry journey. Lesson 16 of 61.

A parallelogram is a quadrilateral whose opposite sides are parallel in pairs. Figures show it with chevrons: one chevron on one pair of opposite sides, two on the other pair.

$Parallelogram ABCD: one chevron on AB and DC, two on AD and BC$

In parallelogram ABCD, AB ∥ DC and AD ∥ BC. Every side is a line crossing two parallel lines. AB, for example, crosses the parallels AD and BC, so all the parallel line rules from the Angles section work inside a parallelogram.

Those rules say a lot about its angles, as you will see next. Drag the shape first and look for what stays the same.

Challenge

ABCD is a parallelogram: C follows your drag so that the opposite sides stay parallel. Drag B along the bottom, or drag D anywhere, and watch the angles at A, B and C. Then press Check.

Try it yourself

$Drag the figure and watch$

Drag the figure and watch

Test yourself

This lesson includes a short quiz. Start the lesson to answer it and track your progress.

All lessons in Polygons & Quadrilaterals

2Regular Polygons

Regular Polygons From an Angle to the Sides Inside a Regular Polygon Recap: Regular Polygons

5Rectangles, Rhombi, Squares

Rectangles The Diagonal of a Rectangle Rhombus Angles Squares Recap: Special Parallelograms

8Area of Parallelograms

Area of a Rectangle A Side from the Area Slide the Top Area of a Parallelogram Recap: Parallelogram Area

11Polygon Chases

Parallel Sides in a Pentagon Marks, Not Looks Pentagon with x Regular Shapes Together Recap: Polygon Chases