Free Quilt Block Pattern
The Proof Positive quilt block features a patch that is not used frequently, but is a step up in difficulty from the half square triangle unit. It is often called a three quarter square triangle patch, as it is comprised of three triangles to make the square.
Half square triangle pieces are used as well as quarter square triangles to make the four patches (the three quarter square triangle units) required for the centre of the quilt block. The completed block is constructed as an uneven nine patch.