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Final: Triangle Meets Line

Part of the Angles section of Coddy's Geometry journey. Lesson 56 of 59.

A triangle ABC sits under a line DE that passes through its top corner C. The line DE is marked parallel to the base AB. Two angles at C are labelled: the one between the line and the side CA, and the triangle's own angle at C.

First decide: does the figure fix the angle at B? If it does, find it.

Challenge

DE passes through C and is marked parallel to AB. Does the figure fix ∠ABC? Answer, and if it does, find it, giving every step its rule. Then press Check.

Try it yourself

$Is there enough information?$

Is there enough information?

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 LineFinal: The Full Round Final: Isosceles Chase Final: Master of Angles