Angles and triangles are labelled in a standard manner.
An angle is named with three letters, in capitals.
When describing an angle using the three letters A, B and C, the angle letter goes in the middle: BAC.
Triangles are labelled with three pairs of letters: a, b and c and A, B and C. The lower case letters, a, b and c represent the lengths, and the upper case letters represent the angles:
For each pair of letters, the length letters are opposite the angle letters.
Fight-angled triangles, label the right angle as C (to make sense of Pythagoras` theorem a2 + b2 = c2). The longest side of a triangle is known as the hypotenuse.
1. In a right-angled triangle, the right angle is labelled C. What is the hypotenuse labelled?
The hypotenuse is the name for the longest side in a right-angled triangle, and is opposite the right angle which should be labelled as C.
2. Two lines AB and CD intersect at a point, E. Give, using a three-letter label, the name of the angle shown with an x.
To make the angle, work along the path A - E - D. This is written as AED.