B
A 15 X 5 C
If BXA = 90 then so is BXC
Note that triangle ABC ≈ AXB ≈ BXC
And we have this realationship
AX / BX = BX / CX
So
15/ BX = BX / 5 cross-multiply
15 * 5 = BX^2
75 = BX^2 take both roots
sqrt ( 75) = BX
sqrt (25) * sqrt (3) = BX
5sqrt (3) = BX
