ANGLES
An acute angle is less than 90º
A right angle is 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