A triangle is a polygon. It is a closed 3-sided shape made up of straight lines. The ‘tri-’ part of the word triangle means three. A triangle has 3 sides and 3 angles. Interior angles are the angles ...
Everything we can see and touch, and quite a lot that we can’t as well, is made of tiny particles called atoms. Some substances, like particles of this iron, contain only one kind of atom. Iron is an ...