Lets assume center point of circle as O
OD is the radius of circle . so OD is also 7
All the sides of the triangle are equal . so angle at the center O is 60 degree.
radius = 7
Length of arc CD = [tex] \frac{theta}{360} * 2*\pi*r [/tex]
= [tex] \frac{60}{360} * 2*\pi*7 [/tex]
= [tex] \frac{1}{6} * 2*\pi*7 [/tex]
= [tex] \frac{7\pi}{3} [/tex]
