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Geometry · Grades 6 to 8

Angles in a triangle worksheet generator

This generator makes angles in a triangle worksheets. Each problem shows a triangle with two angles labeled, and students find the third.

Angles in a triangleLetter 8.5 × 11 in · answer key on the last page
Settings

Settings

In the print window choose Letter and 100% scale, or Save as PDF.

Angles in a triangle
NameDate

The angles in a triangle add up to 180°. Find the missing angle x.

  1. 1.
    26°79°x
    x =
  2. 2.
    40°71°x
    x =
  3. 3.
    72°79°x
    x =
  4. 4.
    43°37°x
    x =
  5. 5.
    34°62°x
    x =
  6. 6.
    30°56°x
    x =
  7. 7.
    59°68°x
    x =
  8. 8.
    47°44°x
    x =
  9. 9.
    75°76°x
    x =
nation1.netSheet 62258893
Angles in a triangle
Answer key
  1. 1.180 − 26 − 7975°
  2. 2.180 − 40 − 7169°
  3. 3.180 − 72 − 7929°
  4. 4.180 − 43 − 37100°
  5. 5.180 − 34 − 6284°
  6. 6.180 − 30 − 5694°
  7. 7.180 − 59 − 6853°
  8. 8.180 − 47 − 4489°
  9. 9.180 − 75 − 7629°
nation1.netSheet 62258893 · answers
PagesFit to widthPrints at 100%

About this worksheet

The three angles in any triangle add up to 180°, so the missing angle is 180 minus the other two. Tearing the corners off a paper triangle and lining them up on a straight edge shows why.

Teaching tip

Ask students whether each answer makes the triangle acute, right or obtuse. It adds a useful second look at every problem.

How to use the generator

Change the settings and the sheet updates as you go. New worksheet gives a fresh set of problems with a new answer key. Print or save PDF opens your browser's print window: pick Letter paper and 100% scale, or Save as PDF to keep a copy.