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In this activity, we will be investigating angle sizes and types of angles.
Here are a few important facts we need to know for our work with triangles!
A right angle is 90º
An acute angle is less than 90º
An obtuse angle is between 90º and 180º
A straight line angle is 180º
A reflex angle is between 180º and 360º
Triangles
A right-angled triangle has one 90º angle.
An isosceles triangle has two equal angles.
An equilateral triangle has three equal angles, each of size 60º
A scalene triangle has three different angles.
Let's try an example question.
Example
Perry draws an angle of 72°
What type of angle is this?
Answer
Angles smaller than 90° are acute.
Perry's angle is acute.
If you want to see this introduction again, just click on the red help button that will appear on the screen.
Let's get practising!
