My friend has ringworm on 3 parts of body. under arm and front and back of leg. could it be from my cat?

Confirmed ?: If confirmed, recurrent ringworm (tinea corporis) reflects a recurrent exposure to a source. There are 3 basic sources;people, animals and the soil. If you have a furry animal a check with the vet may find it. The other two are harder to source. There are also things that may look like ringworm but are really something else.

Cats spread skin inf: Yes, pets can transmit fungal infections to humans when in close contact with them especially if they are not washed regularly.