AB and CD are two common tangents to circles which touch each other at C. If D lies on AB such that CD = 4 cm, then AB is equal to


Given:


CD = 4 cm



Property: If two tangents are drawn to a circle from one external point, then their tangent segments (lines joining the external point and the points of tangency on circle) are equal.


By the above property,


AD = BD = CD = 4 cm (tangent from D)


Now clearly,


AB = AD + BD


AB = AD + BD


AB = 4 cm + 4 cm


AB = 8 cm


Hence, AB = 8 cm

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