focal

Definições

One of two lines perpendicular to the axis of a cone such that the cosine of the angle between the line and the axis is equal to the ratio of the cosines o the semiangles of the cone.

Equivalentes

Exemplos

“Again, if the plane of the impressed couple intersects the mean plane between N and C, it will envelope the cone whose focals are ON, ON′, and whose internal axis is therefore OA.”

Nível QECR