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Year 8 · Angles in parallel lines and polygons
Recall the basic angle rules and notation
Definition
Geometry studies shapes, their properties and their angles. A polygon is a closed shape with straight sides; the more sides it has, the larger the total of its interior angles.
Why Do I Have to Learn This?
Shapes are the building blocks of everything around us. Knowing their properties helps you draw, build and describe the world precisely.
Key Rules:
- 1. Angles in a triangle add to 180°; angles in a quadrilateral add to 360°.
- 2. The interior angles of a polygon add to (sides − 2) × 180°.
- 3. Angles on a straight line add to 180°; around a point, 360°.
Remember:
- •A regular polygon has all sides and all angles equal.
- •Count sides carefully, a pentagon has 5, a hexagon 6, an octagon 8.
- •Right angles are exactly 90°; mark them with a small square.
Acute angle
An angle smaller than 90 degrees.
An angle of 45° is acute.
Animated Example:
3 sides: angles add to 180°
Free Recall the basic angle rules and notation Worksheet
Download free worksheets and practise today.
Every download has a fresh set of questions.
Before this: Angles and polygons (Year 7) · Next: Angles (Year 10 Foundation)
Let’s Practise the Concept
Step 1 of 3
Put the angles in order
Tap them from smallest to largest.
In order so far: nothing yet