Year 10 - Maths
Checking and securing understanding of exterior angles
Angles
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This pupil-friendly study guide includes a unit summary, clear notes, common mistakes, and quick questions with answers.
Unit Summary
In this unit pupils use their knowledge of corresponding, alternate and co-interior angles to reason through and solve more complicated problems.
Lesson Summary
You will learn to find the exterior angle of any regular polygon or deduce the exterior angle of an irregular polygon.
Key Notes
- The sum of the exterior angles of a polygon can be demonstrated using a point.
- The sum of the exterior angles of a polygon can be proven using interior angles and the angles on a straight line.
- An exterior and interior angles pair are supplementary.
Vocabulary To Learn
- Polygon: A polygon is a flat (2D), closed figure made up of straight line segments.
- Regular: A regular polygon has sides that are all equal and interior (inside) angles that are all equal.
- Interior angle: An interior angle is an angle formed inside a polygon by two of its edges.
- Exterior angle: An exterior angle is an angle on the outside of a polygon between an extension of an edge and the adjacent edge.
Common Mistakes To Avoid
- An exterior angle is equal to 360° - the size of the interior angle because angles around a point sum to 360°.
3 Quick Questions (With Answers)
1. Solve this in steps: explain the method from this lesson and why each step matters.
The sum of the exterior angles of a polygon can be demonstrated using a point. The sum of the exterior angles of a polygon can be proven using interior angles and the angles on a straight line.
2. Use this key word in a maths sentence and explain it clearly. 'Polygon'
A polygon is a flat (2D), closed figure made up of straight line segments. Use this word when showing your method, then check your final answer is reasonable.
3. Spot and fix this common maths mistake.
Mistake: An exterior angle is equal to 360° - the size of the interior angle because angles around a point sum to 360°. Correction: An exterior angle is an angle on the outside of a polygon between an extension of an edge and the adjacent edge.
More Lessons In This Unit
- Checking and securing understanding of advanced angle facts Study Guide
- Checking and securing understanding of angle notation and drawing/measuring angles Study Guide
- Checking and securing understanding of basic angle facts Study Guide
- Checking and securing understanding of interior angles Study Guide
- Checking and securing understanding of polygons Study Guide
- Checking and securing understanding of properties of shapes Study Guide
- Checking and securing understanding on chains of reasoning with angle facts Study Guide
- Forming equations with angles Study Guide
- Problem solving with angles Study Guide
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