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Right Triangles

Part of the Angles section of Coddy's Geometry journey. Lesson 45 of 62.

A right triangle spends 90° of its budget on the square-marked corner. The other two corners share what is left: 90°. So the two non-right angles of a right triangle are complementary, and the corner chapter returns with a triangle wrapped around it.

$A right triangle with the right angle at the apex and a 28 degree base angle$

In the figure the apex square takes its 90, so 28 + y = 90 and y = 62. No need to write the full three-corner sum: the square pre-pays half the budget, and the shortcut is yours.

Challenge

Medium

The triangle in the figure is right-angled at the apex. One base angle measures 38°, the other x°.

$A right triangle with the right angle at the apex, base angles 38 and x degrees$

Find x.

Try it yourself

x + 38 = 90

Solve for x

Test yourself

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

All lessons in Angles

2Straight Lines and Supplements

Angles on a Line Supplementary Angles Three Angles on a Line 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

8Transversal Problems

Both Angles Labeled Verticals Meet Parallels From Figure to Equation Alternate with Algebra 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

Complementary Angles Finding the Complement Perpendicular Lines 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 AnglesRight TrianglesRecap: The Budget

12Final Challenges

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