Menu

Final: The Angle Chase

Part of the Angles section of Coddy's Geometry journey. Lesson 55 of 59.

Two parallel lines, AB and DE, hold a triangle between them: its top corner P is on AB and its other two corners Q and R are on DE. The sides PQ and PR are extended below DE. One angle below the line is known at Q, and one at R.

Find the triangle's angle at P. No single rule reaches it from the labels, so plan a chase: which angles can you reach first, and which rule finishes?

Challenge

AB ∥ DE, and the triangle PQR has P on AB and Q, R on DE. Find the angle QPR, giving every step its rule, then press Check.

Try it yourself

$Find the marked part of the figure$

Find the marked part of 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 Lines Corresponding Angles Alternate 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 ChaseFinal: Triangle Meets Line Final: The Full Round Final: Isosceles Chase Final: Master of Angles