Dog
The answer to this riddle is a man. In the morning of his life he crawls or goes on four feet, in the afternoon of his life he walks on two feet, and in the evening of his life he uses a cane and goes on three feet.
When he is standing still he only has two feet, but when he moves around he has three.
A yard is three feet, two yards are six feet, the difference is three feet.
The riddle "What has two eyes and three feet?" refers to a person who is wearing a pair of eyeglasses (the "two eyes") and using a cane for support (the "three feet"). The two eyes represent the glasses, while the three feet come from the combination of two human feet and the one foot of the cane. It's a playful way to describe a person with a specific accessory.
You have given three dimensions; square feet has only two dimensions. Do you mean cubic feet?
One yard is three feet so four yards are twelve feet. Twelve subtract two is ten so ten feet remains. Hope this helps. :)
11 feet
Two pirates.
6 cubic feet
There are three feet in one yard, so a diameter of two yards is six feet. The radius is half the diameter, so the radius is three feet.
6 square feet.
two feet high three feet long