Curriculum
Mathematics — Second Preparatory
Unit 1: Real Numbers
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Unit 2: Algebra
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Unit 3: Geometry
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Congruence
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Congruence — Lesson quiz
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The Pythagorean Theorem
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The Pythagorean Theorem — Lesson quiz
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Applications of Parallelism
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Applications of Parallelism — Lesson quiz
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Medians of a Triangle
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Medians of a Triangle — Lesson quiz
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The Isosceles Triangle
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The Isosceles Triangle — Lesson quiz
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Interior and Exterior Angles of a Polygon
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Interior and Exterior Angles of a Polygon — Lesson quiz
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Unit 4: Statistics
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Text lesson
Interior and Exterior Angles of a Polygon
Interior and Exterior Angles of a Polygon
Sums of interior and exterior angles
Sums of interior and exterior angles
- If a polygon has n sides
- then:
| Quantity | Formula |
|---|---|
| Sum of the interior angles | (n − 2) × 180° |
| Sum of the exterior angles (one at each vertex) | 360° |
| Interior angle of a regular polygon | (n − 2) × 180° ÷ n |
| Exterior angle of a regular polygon | 360° ÷ n |
- The formula for the interior angles can be explained by dividing the polygon into triangles from one vertex.
- There are n − 2 triangles, and each has angles summing to 180°.
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