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Grade 10 triangle angle sum worksheets

HSG-CO.C.10 Measurement and geometry

Printable triangle angle sum worksheets for grade 10, aligned to Common Core standard HSG-CO.C.10. Angles add to 180°.

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Sample problems

  1. A triangle has angles of 84° and 32°. What is the measure of the third angle? 64°
  2. A triangle has angles of 74° and 47°. What is the measure of the third angle? 59°
  3. A triangle has angles of 59° and 65°. What is the measure of the third angle? 56°
  4. A triangle has angles of 85° and 48°. What is the measure of the third angle? 47°
  5. A triangle has angles of 95° and 27°. What is the measure of the third angle? 58°
  6. A triangle has angles of 87° and 48°. What is the measure of the third angle? 45°
  7. A triangle has angles of 38° and 28°. What is the measure of the third angle? 114°
  8. A triangle has angles of 27° and 31°. What is the measure of the third angle? 122°

These eight are one sample at medium difficulty — the generator makes a different set every time.

A worked example

A triangle has angles of 84° and 32°. What is the measure of the third angle? 64°

  1. The three angles of a triangle add up to 180°
  2. 84 + 32 = 116
  3. 180 − 116 = 64°

Every problem on the answer key can show its steps like this — turn on “Show steps” before downloading.

About these worksheets

Each problem states its own measurements, so the reasoning is the same but the arithmetic is new every time. Every sheet is generated fresh, so you can print a new one on the same skill as often as you need — different numbers, same difficulty.

Pick how many problems you want and whether they should be easy, medium or hard, then download a PDF with a matching answer key. The key can show the worked steps for every problem, which is what a parent needs to see where a wrong answer went wrong.

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