Label the angles and side, leaving the construction lines. Triangles A and D can be constructed using a protractor and ruler. Triangle A includes two angles and the side between them (ASA).

But many people wouldn't be able to explain the meaning of the triangle symbol on a clothes label, despite its presence on hundreds of clothing items. READ MORE: BBC TV Licence could be reduced to ...

The white triangle on clothes labels can take four forms: an empty triangle, a triangle with a cross through it, and a triangle with two diagonal lines through it. It could also be a triangle with ...