PRESS the button and observe. Some things change but some don't. The angles at A and C change, but the chain remains vertical (perpendicular to the ground because of gravity) so the angle B doesn't change, it's always 90°. The chain changes its length and so too does the ground distance between A and B. The crane does not change its size. It is opposite the right angle at B = 90° which makes the crane a HYPOTENUSE.
Learn: From the rotating angle at A, SINE is the name of the trigonometric function (or relationship) between the Chain and the Crane (opposite and hypotenuse). It makes no sense that the chain could ever be longer than the crane. SINE is a value between 1 and 0. 1 at 90° and 0 at 0°. Try them for yourself.
