The Missing Angle
Part of the Angles section of Coddy's Geometry journey. Lesson 23 of 62.
A small square marks a right angle of exactly 90°. Include that measure in your calculation even when the diagram does not label it with a number.
The square marks a 90° angle, and the other known angle is 130°. The angles complete a full turn, so y + (90 + 130) = 360. This gives y + 220 = 360 and y = 140. Include the right angle even though its measure is shown by a mark rather than a number.
Challenge
EasyThree angles share the point: a right angle, 145° and x°.
Find x.
Try it yourself
Solve for x
Test yourselfThis lesson includes a short quiz. Start the lesson to answer it and track your progress.
All lessons in Angles
1Meet the Angle
Your First AngleNaming AnglesAdding Adjacent AnglesDegrees and the Full TurnAcute, Right, ObtuseRecap: Adjacent Angles4Vertical Angles
Linear PairsVertical Angles Are EqualSolving with VerticalsAll Four AnglesRecap: At the Crossing2Straight Lines and Supplements
Angles on a LineSupplementary AnglesThree Angles on a LineWrite the EquationRecap: Along the Line5Around a Point
Angles Around a PointThe Missing AngleEqual SlicesFour Angles, One PointRecap: The Full Turn3Right Angles and Complements
Complementary AnglesFinding the ComplementPerpendicular LinesEqual Parts of a CornerRecap: The Right Corner6The Angle Bisector
The Angle BisectorBisected ExpressionsBisecting a Straight AngleRecap: Split in Half