Angle rules
Angles on a straight line add up to 180 degrees, angles around a point add up to 360 degrees, and angles in a triangle add up to 180 degrees.
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Analogy
Like slices of pizza: all the slices together make the full circle.
Example
Triangle angles 50 and 60Third angle = 180 - 50 - 60= 70 degrees
In practice
Builders use these facts to check corners and cut roof beams at the right angle.
Practice
Flashcards
- How many degrees are there in a triangle?180 degrees.
Questions people ask
Why do the angles in a triangle add to 180 degrees?
If you tear off the three corners of any triangle and line them up, they form a straight line, which is 180 degrees. This works for every triangle, whatever its shape. It is a fact you can rely on to find a missing angle.
What are vertically opposite angles?
When two straight lines cross, they make four angles. The angles directly opposite each other are equal. They are called vertically opposite angles. If one is 65 degrees, the one facing it across the crossing is also 65 degrees. Their equal sizes are a useful way to find missing angles.