Area of the following rectangle

In trapezoid abcd, ac is a diagonal and ∠abc≅∠acd. find ac if the lengths of the bases bc and ad are 12m and 27m respectively.

Can anyone explain to me how to do this? anything will .

Enter your answer and show all the steps that you use to solve this problem in the space provided. write a list of steps that are needed to find the measure of ? b .