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αAπΣ∞∂θ√x²≠∫÷≤%+−½αβΔλφ³≈∑°
  1. Home/
  2. Mathematics/
  3. Grade 7/
  4. Unit 4/
  5. Angle Relationships
Grade 7 · Unit 4Topic 2 of 4~20 min

Angle Relationships

Use complementary, supplementary, vertical, and adjacent angles to find unknowns.

All topics in this unit
αAπΣ∞∂θ√x²≠∫÷≤%+½αβΔ
Step 1 · Learn

Walkthrough

Read this first — it covers the idea in plain language with a worked example.

The key relationships

  1. 1Complementary angles add to 90°.
  2. 2Supplementary angles add to 180°.
  3. 3Vertical angles (across an X) are equal.
  4. 4Adjacent angles share a side and a vertex.
Worked example

Two angles are supplementary. One is 110°. Find the other.

  1. →Supplementary angles add to 180°.
  2. →180° - 110° = 70°.

Set up an equation

When an unknown angle is part of a relationship, write an equation (like x + 110 = 180) and solve.

αAπΣ∞∂θ√x²≠∫÷≤%+½αβΔ
Step 2 · Watch

Video walkthrough

A short video that walks through this topic.

Math Antics

Angle Basics

Right, acute, obtuse, complementary, and supplementary angles.

Watch on YouTube
αAπΣ∞∂θ√x²≠∫÷≤%+½αβΔ
Step 3 · Practice

Practice

Try a worksheet or work through some problems before the quiz.

Khan Academy

Angle relationships

Open resource
Math Worksheets 4 Kids

Angles worksheets

Open resource
πΣ√≠≤+αβΔπΣx²θ÷+
Step 4 · Check

Quick check

A couple of questions to make sure this topic stuck. Retake as many times as you want.

Angle Relationships

Question 1 of 2

Easy

An angle is complementary to a 35° angle. What is its measure?

αAπΣ∞∂θ√x²≠∫÷≤%+½αβΔ
←Previous · Topic 1 of 4Scale Drawings→Next up · Topic 3 of 4Circumference & Area of Circles