I need help with question 18. The answer is53√3 ft^2. But how do I get there?

Answer:
52√3 ft²
Step-by-step explanation:
sin 60° = (√3) / 2 = h/8
h = 8 x (√3) / 2 = 4√3
cos 60° = 1/2 = a/8
a = 4 b = 15-4 = 11
area = left triangle + right rectangle
area = (4*4√3) / 2 + 11*4√3
= 8√3 + 44√3
= 52√3