Question

if the third proportional to 7and x is,find the value of x

Answer 1

The third proportional of two numbers a and b is defined to be that number c such that a : b = b : c. So you want to find a number c such that 12 : 18 = 18 : c. That number is 27. If BD = AC, then the 3rd proportional to AB and AC is CE.