Image caption, To do this, split the parallelogram into a right-angled triangle and a trapezium. A trapezium is a quadrilateral with one pair of parallel sides. Image caption, Move the right ...

Move the shape of the peaks to create different quads . Is it possible to make a square that is not also a rectangles ? A diamond that is not also a parallelogram ? Why? Drag the vertices to create ...

Surprisingly, when the quadrilateral is a parallelogram, like in a scissor lift, or “cyclic”, when the endpoints lie on a circle, the bar framework can move. Tweaking the ratios of the middle ...