The ‘legs’ are the two equal sides. The third side is called the base, even when the triangle is in a different orientation. An isosceles triangle has two angles that are the same size.

The orientation of the triangle means that the base is not necessarily horizontal or the lowest side of the shape. Image caption, For triangles that are not right-angled, the base is one of the ...

(typical responses: size, all triangles, all coloured, all have three sides, all pointed the same way (orientation), all have angles). 2. After the initial discussion about the static triangle images, ...