RulesMath · P4 to P6Angles
Angles Must-Know Rules
Every angle question uses one of these six rules. Memorise them.
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1
Straight Line
Angles on a straight line add up to 180°.
2
Point
Angles around a point add up to 360°.
3
Triangle
Interior angles of a triangle add up to 180°.
4
Quadrilateral
Interior angles of a 4-sided shape add up to 360°.
5
Vertically Opposite
When two lines cross, opposite angles are equal.
6
Isosceles Triangle
The two base angles are equal.
⚠️ Common Mistakes
Don't fall into these traps
- ✕Assuming a triangle is isosceles without proof
- ✕Confusing 180° and 360° rules
- ✕Skipping the reason line in working
Teacher Hidayah's Tip
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Always write the reason (e.g. 'angles on a straight line') next to your working.
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Sample Question
Try it, then read the worked solution
Question
In triangle ABC, ∠A = 50°, ∠B = 60°. Find ∠C.
Worked Solution
- 1Sum of angles in triangle = 180°
- 2∠C = 180° − 50° − 60°
- 3∠C = 70°
Everything for Angles
Each topic in the library comes with the full 5-piece bundle.
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Before-Class Prep
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After-Class Practice
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Downloadable Notes
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One-Page Mind Map
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Mistake Fix Zone