tangent of circle

The tangent of may be defined by using whatever of the below three characterisations.

The is a line

• whose distance from the centre of the circle is equal to the radius of the circle;

• that is perpendicular to a radius of the circle and passes through the end point of the radius lying on the circumference;

• that has only one common point with the curve.

Note. The tangent of ellipse may also be defined by using the third characterisation.

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