8th Grade Angles In Triangles Worksheets

8th Grade Angles in Triangles: use the triangle angle sum to find missing angles. Every worksheet is free, prints as a PDF with an answer key, and can be assigned online. The ones teachers open most are first.

← All 8th grade topics 8.G.5

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Finding a Missing Angle in a Triangle

8g5

• Add the two known angles of a triangle.
• Subtract from 180 to find the third.
• Check the answer against the drawing.

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Using the Angle Sum of a Triangle

8g5

• Use the fact that a triangle's angles add to 180 degrees
• Find a missing angle when two angles are equal
• Add two angle measures to check a statement
• Tell a true statement about angles from a plausible one

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Why the Angles of a Triangle Add to 180

8g5

• See that the three corners of a triangle fit along a straight line.
• Say that a straight line measures 180 degrees.
• Use the fact to find a missing angle.

More 8th grade topics

Square Roots & Irrational Numbers 16Identifying Functions 9Transformations 5Scientific Notation 7Slope & Rate of Change 8Comparing & Modeling Linear Functions 11Laws of Exponents 3Linear Equations & Systems 2Pythagorean Theorem 2Congruent & Similar Figures 5Volume of Cylinders, Cones & Spheres 2