In a 30 60 90 triangle, the "middle-sized" side = the short side multiplied by the square root of 3.
so the "middle-sized" side = x * square root of 3.
Source:
http://www.1728.org/trig2.htm
The Answer To Your Question Is D 64
∠KMN = (1/2)*arc KN . . . . . . this relationship is true of any inscribed angle. (It is a useful relationship to remember.)
= 95°/2
= 47.5°
Sum of interior angles= 180