Here are a few important facts we need to know for our work with triangles!
Angles
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.
That's a lot to remember, but it's all very important stuff to know and will really help you in your geometry work!
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!