dodecagon.
http://wiki.answers.com/Q/What_is_a_shape_that_has...

The shape that has 4 sides and 3 corners would have to be a triangle. There are three particular sides along with the bottom which would equal 4 sides.
http://www.ask.com/webanswers/Science/Mathematics...

In geometry, a dodecagon is any polygon with twelve sides and twelve
http://www.chacha.com/question/whatshapehas12s...

Icosikaitrigon , or tricosagon.
http://wiki.answers.com/Q/What_shape_has_23_sides
