11yd is the diameter and circumference is 2πr = 2π(d/2) = πd = 11π yd
A model shows the visualize of what you need to do in order to complete the problem your asked. It can also show important steps and make it easier for you to answer the question, like length×height×width.
A two-dimensional shape has length and width. A three-dimensional solid shape also has depth. Three-dimensional shapes, by their nature, have an inside and an outside, separated by a surface. All physical items, things you can touch, are three-dimensional.
