Answer:
(C)23cm
Step-by-step explanation:
We apply the theorem that tangents to a circle from a given point are equal.
Let X, Y and Z be the tangent points as shown in the attached circle.
By the theorem above:
|CX|=|CY|=4cm
|BY|=|BZ|=10cm
Since |AC|=17cm and |CX|=4cm
|AX|+|CX|=17
|AX|+4=17
|AX|=17-4=13cm
By the same theorem, |AX|=|AZ|
Therefore:
|AB|=|AZ|+|BZ|=13+10=23 cm
