To find the length of fence you need to find length of 3rd side of triangle. And then find the perimeter of triangle.
As triangle is SAS, to find the length of 3rd side we have to use law of cosine
a2 = c2 + b2 - 2cb cos A
=(37)2 + (30)2 - 2(37)(30)cos 62
take square root of both sides
a = 35 ft
Perimeter of triangle ABC=35 +30+37=102 ft
102 ft fence Mary need to buy