Split the parallelogram into a right-angled triangle and a trapezium. Move the triangle to the other end of the shape, making a rectangle. The length of the rectangle is the base of the parallelogram.

the researchers started showing them sets of shapes that included squares, parallelograms, or irregular quadrilaterals. Sponsor Message The crows might see, for example, five perfect squares along ...

To demonstrate which shape they determined to be the 'intruder ... the trials featured such quadrilaterals as the classic square, rhombus, isosceles trapezoid, right hinge (shown above), and ...

But cubes squished and stretched into parallelepipeds (shapes with six parallelograms for faces) can fill space, too. And in 1885 Russian crystallographer Evgraf Fedorov cataloged a set of five ...

Could the crows distinguish regular shapes, like squares or parallelograms, from irregular quadrilaterals? So he had a couple crows learn a new game. The birds would see six shapes on the screen ...