Arthur D. answered 04/11/18
Tutor
4.9
(290)
Forty Year Educator: Classroom, Summer School, Substitute, Tutor
Assuming a regular hexagon inscribed inside of a circle !
There are 6 congruent triangles. Take one of them
Draw the altitude and call it h.
Call the radius r.
Call half of a side x.
Call the top right-side angle θ.
cosθ=h/r and sinθ=x/r
h=rcosθ and x=rsinθ
A=(1/2)(b)(h)
(1/2)(b)=x
A=xh
substituting
A=rsinθrcosθ
A=r2sinθcosθ
from trig identity sin2θ=2sinθcosθ
A=r2(1/2)sin2θ
The angle 2θ at the apex is determined by the number of sides, n
Therefore 360/n=2θ
A=(1/2)(r2)sin(360/n)
A=(1/2)(102)sin(360/6)
A=(1/2)(100)(sin60º)
A=50(√3/2)
A=25√3 for one of six congruent triangles
multiply this area by 6 to get the area of the hexagon
A=6*25√3
A=150√3 square units which is choice C.