Question

Given that CD = 15 and is a tangent to the circle, and BD = 12, which is the length of AB?

Answer 1

where is the figure ?

Answer 2

just use proportion :
BC/AB = AB/BD
27/AB = AB/12
AB*AB = 27*12
AB^2 = 324
AB = sqrt(324)
AB = 18

Answer 3

thanks

Answer 4

maybe this link can help u to understanding it
http://mathworld.wolfram.com/CircleTangentLine.html

Answer 5

welcome