With 0 as a center and a radius of about 1 1/4 inches draw the given circle. Assume some point P on the circumference and join the point P with the center 0. By the method given in Problem 6, Plate IV, construct a perpendicular to P 0, which perpendicular will be the desired tangent to the circle at the point P.


A line perpendicular to a radius at its extremity is tangent to the circle.