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Trapezoids

Part of the Polygons & Quadrilaterals section of Coddy's Geometry journey. Lesson 25 of 59.

A trapezoid is a quadrilateral with exactly one pair of parallel sides. The parallel sides are its bases, and the other two sides are its legs. In trapezoid ABCD, AB ∥ DC.

$Trapezoid ABCD with AB parallel to DC: 70 degrees at B and 110 degrees at C$

Each leg crosses the two parallel bases, so the two angles along a leg are co-interior and add up to 180°. Here ∠B = 70°, so ∠C = 110°. The angles along the other leg pair up the same way, but A and B are not linked: AD and BC are not parallel.

Challenge

ABCD is a trapezoid with AB ∥ DC. Find the angle at D, marked ?, then press Check.

Try it yourself

$Find the marked part of the figure$

Find the marked part of the figure

All lessons in Polygons & Quadrilaterals

2Regular Polygons

Regular Polygons 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

3Exterior Angles

Exterior Angles Exterior Angles Make 360°Regular Exterior Angles Sides from the Exterior Recap: Exterior Angles

6Trapezoids and Kites

TrapezoidsIsosceles Trapezoids Trapezoids with x Kites Recap: Trapezoids and Kites

9Area of Trapezoids

Area of a Trapezoid A Missing Base Find the Height First Trapezoids by Area Recap: Trapezoid Area

12Final Challenges

Final: The Garden Bed Final: Enough to Finish?Final: The Ramp Final: The Gable Wall Final: The Star Point