In triangle ABC, use the Law of Cosines to find the base BC = 8.728.
Since it is an equilateral triangle that means all 3 sides have the same length of 8.728 and the three angles are the same:A = B =C = 60 degrees.
In triangle BDC, angle DBC =9.896 degrees which means angle DBA = 60 - 9.896 =50.104 degrees.
In triangle ABD, we have its two sides AB and BD and the angle DBA between them. Now, we can use the Law of Cosines again to solve for x.
And x =6.708 and x^2 =6.708^2 =~45