Angle Sum of Triangles & Polygons (Year 8)
Free printable UK Year 8 (Key Stage 3) maths worksheet: find missing angles using the triangle angle-sum fact and the polygon interior/exterior angle formulas.
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Grade 7 · Math worksheet
Name
Date
Math
Angle Sum of Triangles & Polygons
Use the triangle angle-sum fact, the polygon interior angle-sum formula, and the regular-polygon exterior angle formula to find each missing angle.
- 1.A triangle has angles of 28 degrees and 57 degrees. Find the 3rd angle.
- 2.A triangle has angles of 52 degrees and 20 degrees. Find the 3rd angle.
- 3.A triangle has angles of 67 degrees and 93 degrees. Find the 3rd angle.
- 4.Find the sum of the interior angles of a 14-sided polygon (14 sides).
- 5.Find the sum of the interior angles of a 11-sided polygon (11 sides).
- 6.Find the sum of the interior angles of a hexagon (6 sides).
- 7.Find the sum of the interior angles of a heptagon (7 sides).
- 8.Find (a) the exterior angle, and (b) the interior angle, of a regular dodecagon (12 sides).
- 9.Find (a) the exterior angle, and (b) the interior angle, of a regular 20-sided polygon (20 sides).
- 10.Find (a) the exterior angle, and (b) the interior angle, of a regular nonagon (9 sides).
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