18. (4 points) Zeinab is creating a flower garden in her backyard. She builds the garden in the shape of a triangle, using the fence and the shed wall as a corner for the garden. The garden has a side length of 8.1 ft along the fence, a side length of 9.9 ft along the shed, and a side length of 10.7 ft in her yard. Determine the measure of the angle created by the corner joining the fence and the shed, rounded to the nearest degree. Diagram: Formula: Substitution: Solve