JEE-Mains 2015 (27/30)

Geometry Level 3

If the angles of elevation of the top of a tower from three collinear points \(A, B,\) and \(C\), on a line leading to the foot of the tower, are \(30^{\circ},45^{\circ},\) and \(60^{\circ},\) respectively, then the ratio \(AB:BC\) is \(\text{__________}.\)