Classifying three-dimensional shapes

Self-assessment questions

Why is it not possible to have an equilateral, right-angled triangle or an equilateral, obtuse-angled triangle?

What are the sizes of the three angles in a right-angled, isosceles triangle?

Which of the following shapes tessellate? (a) a parallelogram; (b) a regular pentagon; and (c) a regular octagon.

How many planes of symmetry can you identify for a cube?

True or false?

(a) All parallelograms are rhombuses;

(b) All squares are rectangles;

(c) All cubes are cuboids;

(d) All squares are rhombuses:

(e) All pentagons have five equal sides:

(f) All isosceles triangles are acute-angled triangles.