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Corresponding Angles

Part of the Angles section of Coddy's Geometry journey. Lesson 29 of 59.

At each crossing the transversal makes four angles: one above the parallel and to the left, one above and to the right, and two below. Angles in the same position at the two crossings are corresponding angles.

$Parallel lines cut by a transversal: corresponding angles of 65 degrees, both above the line and left of the transversal$

In the figure both 65° angles sit above their parallel and to the left of the transversal. They are equal because the lower crossing is a copy of the upper one, slid along the transversal: the parallels point the same way, so nothing about the crossing changes. Trace the two angles and the lines between them and you draw a letter F, which is why people call this the F shape.

The rule is Corresponding angles, and it needs the chevrons. Without parallel lines the two crossings can lean differently and nothing matches.

Challenge

AB and CD are parallel, cut by the transversal GH. Tap the angle corresponding to ∠1, then press Check.

Try it yourself

$Find the right part on the figure$

Find the right part on the figure

All lessons in Angles

1Meet the Angle

Your First Angle Angles on a Line Degrees and the Full Turn Across the Crossing

4Vertical Angles

Two Lines Cross Vertical Angles Are Equal Solving with Verticals All Four Angles Recap: At the Crossing

7Parallels and Transversals

Parallel LinesCorresponding AnglesAlternate Angles Co-interior Angles Which Rule Is It Recap: The Three Pairs

10Isosceles and Equilateral

Base Angles Are Equal Finding the Apex Which Angles Match Equilateral Angles Isosceles at Work Recap: Twin Corners

2Naming and Equations

Adding Adjacent Angles Write the Equation Recap: Along the Line

5Around a Point

Angles Around a Point The Missing Angle Equal Slices Four Angles, One Point Recap: The Full Turn

8Angle Chases

Verticals Meet Parallels Is There Enough?From Figure to Equation Both Angles Labeled Recap: Through the Strip

11The Exterior Angle

The Exterior Angle Using the Shortcut Two Roads, One Answer Exterior in the Wild Recap: Outside View

3Right Angles and Complements

The Square Mark Complementary Angles Perpendicular Lines Finding the Complement Equal Parts of a Corner Recap: The Right Corner

6The Angle Bisector

The Angle Bisector Bisected Expressions Bisecting a Straight Angle Recap: Split in Half

9Triangle Angle Sum

The 180 Rule Finding the Third Angle Two Unknown Angles Right Triangles Recap: The Budget

12Final Challenges

Final: The Angle Chase Final: Triangle Meets Line Final: The Full Round Final: Isosceles Chase Final: Master of Angles