AC9M7M05Year 7MeasurementPractised on site

AC9M7M05 — Year 7 Measurement

Official Curriculum Content Description:

demonstrate that the interior angle sum of a triangle in the plane is 180° and apply this to determine the interior angle sum of other shapes and the size of unknown angles

Worked Examples (1)

Example 1Interior Angle Calculations in Polygons
The sum of the interior angles of a polygon is 12060°. How many sides does the polygon have?
Common mistake: Divided sum by 180 without adding 2
Correct Answer:6969
Worked Solution:
Interior angle sum = (n − 2) × 180° = 12060°. So (n − 2) = 12060 ÷ 180 = 67, which gives n = 69.

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