12. SINCE ABIS TANGENT TO CIRCLE CAT POINT B, WEAND THEREFORE,X2– 4...
28.12. Since ABis tangent to circle Cat point B, weand therefore,x
2
– 4x+ 4 = 0. After factor-ing, this equation results in (x– 2)(x– 2) =know (by definition) that it is perpendicularto the radius of the circle. The radius is BC.0. Hence, a possible value is 2.