This linkage converts motion along a circle[br]to motion along a straight line.[br][br]The two GREEN lines are of equal length and fixed at their common[br]end point.[br][br]The four BLUE lines are of equal length forming a rhombus.[br]Two opposite vertices of the rhombus are connected to the ends [br]of the GREEN lines.[br][br]Drag the GOLD dot along the circle. Prove that the BLUE dot[br]moves along a straight line.