Four Angles, One Point

Part of the Angles section of Coddy's Geometry journey. Lesson 25 of 62.

When one angle in a full turn is unknown, first add the known angle measures. Subtract their total from 360° to find the unknown angle.

$Four angles around a point: 100, 105, 75 and y degrees$

In the figure, y + (100 + 105 + 75) = 360. The known measures add to 280°, so y + 280 = 360. Subtract 280 to find y = 80.

Challenge

Medium

Four angles share the point: 130°, 95°, 85° and x°.

$Four angles around a point: 130, 95, 85 and x degrees$

Find x.

Try it yourself

x + (130 + 95 + 85) = 360

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

5Around a Point

8Transversal Problems

11The Exterior Angle

3Right Angles and Complements

6The Angle Bisector

9Triangle Angle Sum

12Final Challenges