Question

You plan to sew two triangles of fabric together to make a square for a quilting project. The triangles are both right triangles and have the same side and angle measures. What must also be true about the triangles in order to guarantee that the opposite sides of the fabric square are parallel? Explain.

Answer 1

since the triangle is 90 degrees the other have to be 45 
90+90+45+45+45+45=360
360 degrees in a square