If 2 triangles are similar, the ratio of one side of the triangle to the corresponding side of the other is always same for all 3 sides. We can make use of this rule to calculate the length of sides. From the image, 3 / 15 = 6 / x Simplify, 1 / 5 = 6 / x Use cross method to solve this. 5 x 6 = 1 x x X = 30 Therefore the length of x is 30ft., A.
