Tangents to Circles

Tangent to a circle

A straight line that touches the circle at only one point

Point of tangency

The point of contact between tangent and the circle

When tangent and the radius intersect at the tangent point, a right angle is formed

The properties related to two tangents to a circle

The relationship of the angle between tangent and chord with the angle in the alternate segment which is subtended by the chord

A common tangent to two circles

A straight line that is a tangent to both the circles

One common tangent

Two circles of equal sizes or different sizes that are overlapping

Two common tangents

Two circles of equal sizes or different sizes that are intersecting

Three common tangents

Two circles of equal sizes or different sizes that are touching at one point

Four common tangents

Two circles of equal sizes or different sizes that are not touching each other