Mon Prof Augmenté
Torn Corners on a Ruler
Age 12 · Maths
A paper triangle has its three corners torn off. Along a ruler, the three corners meet to make a straight line, showing 180°.
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In the picture
- Red torn corner: one angle of the triangle.
- Blue torn corner: another angle of the triangle.
- Yellow torn corner: the third angle of the triangle.
- Paper triangle: the shape left after its three corners are removed.
Examples
- A triangular ramp support: if two corner angles are known, the third can be found.
- A pizza slice shaped like a triangle: find a missing corner angle.
Key takeaways
- Every triangle has angles that add to 180°.
- To find a missing angle, subtract the two known angles from 180°.
Quiz: Torn Corners on a Ruler (Age 12)
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What do the three angles of any triangle add up to?
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If you know two angles of a triangle, how do you find the third angle?
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Two angles of a triangle are 50° and 60°. What is the third angle?
The answers, each with its explanation, are in the app. This lesson has left the free week, so its quiz is part of the subscription.
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