Question

what formula do you use to find the value of x in a pair of similar figures. The figures are 1.5ft & x 3ft & 6ft

Answer 1

for similar fig.
1.5/x =3/6
x=2*1.5=3(by cross multiplication)

Answer 2

Lets call the numbers L1=1.5 and L2=x; R1=3 and R2=6

You can set this up a few ways.

L1/L2 = R1/R2

L1/R1 = L2/R2

L2/L1 = R2/R1

and so forth.

I tend to use the most basic: L1/L2 = R1/R2

1.5/x = 3/6
1.5 = 3x/6
1.5/3 = x/6
1.5 (6/3) = x
1.5 (2) = x
3=x