65. Equation to the hyperbola, vertex ▲ being origin,

66. Polar equation to the hyperbola, centre being pole,

67. Polar equation to the hyperbola, focus being pole,

69. Equation to the hyperbola referred to its asymptotes,

70. Equation to the tangent at point (x'y'),

71. Equation to the normal through (x'y'),

82. The normal at any point bisects the exterior angle between the focal distances of that point.

General Equation to the Section of a Cone

Made by a plane inclined to the axis of the cone at angle

π

a, at a perpendicular distance d sin vertex: 2a being the vertical angle of the cone.

from the

1. If 4 = interior angle of a regular figure of n sides,