Figure 4-43.-Conic sections: ellipse, parabola, and hyperbula (left to right).Figure 4-44.-Ellipse by pin-and-string method.ELLIPSE BYC as a center, strikePIN-AND-STRING METHODF and F´. The pointsarcs intersecting AB atF and F´ are called thefoci of the ellipse. Set a pin at point C,The dimensions of an ellipse are given in termsanother at F, and a third at F´. Tie theof the lengths of the major (longer) and minorend of a piece of string to the pin at F, pass the(shorter) axes. Figure 4-44 shows a method of con-string around the pin at C, draw it taut, and fastenstructing an ellipse that is called the pin-and-stringit to the pin at F´. Remove the pin at C, place themethod. The problem is to construct an ellipsepencil point in the bight of the string, and drawwith a major axis, AB, and a minor axis, CD. Setthe ellipse as shown in view C, keeping the stringa compass to one-half the length of AB, and, withtaut all the way around.4-15
Integrated Publishing, Inc. - A (SDVOSB) Service Disabled Veteran Owned Small Business
