Ruler null for quadratic curve of parabola, hyperbola and ellipse

摘要

PURPOSE:To simply draw a quadratic a curve by forming a diameter groove to a ruler board on which a circle and the diameter line passing through the center point of the circle are displayed so as to cross said diameter line at right angles in a state extending to the outside of the circle at least in one direction thereof and providing a shaft stop hole to at least one of the intersecting points of the diameter axial line of said diameter groove and the circle. CONSTITUTION:To a ruler board 3 on which a circle 1 and the diameter line 2 passing through the center point of the circle 1 are displayed, the diameter groove 4 crossing the diameter line 2 at a right angle is formed so as to extend to the outside of the circle 1 at least in one direction thereof and a shaft stop hole 6 is provided to at least one of the intersecting points of the diameter axial line 5 of the diameter groove 4 and the circle 1. By this constitution, a quadratic curve such as a parabola, a hyperbola or an oval can be simply drawn.