We're given two angles and an included side and we want to solve for a side opposite one of the given angles. Using the typical triangle notation we have
b=AC=91.791 meters
A=76.833 degrees
C=31.683 degrees
and our task is to find c=AB.
To apply the Law of Sines we need B, which we get since the triangle angles add to 180 degrees:
B = 180 - A - C = 180 - 76.833 - 31.683 = 71.484 degrees
Now the Law of Sines says
[tex] \dfrac{b}{\sin B} = \dfrac{c}{\sin C}[/tex]
[tex]c = \dfrac{b \sin C}{\sin B}[/tex]
[tex] c = \dfrac{ 91.791 \sin 31.683^\circ }{\sin 71.484 ^\circ} = 50.842 [/tex]
Answer: 50.842 meters