Respuesta :

sqdancefan
There's a very simple rule for geometries like this. The measure of the arc is double the measure of the angle. It helps to remember this.

Your angle is 65°.
The measure of the arc is 2×65° = 130°.
jcherry99
You need to use the central angle.
If you know the radius or how CD works (does it go through the center), then  the answer will be less vague. The central angle = 2 * 65 = 130
the length of BC is 

130/360 * 2*pi*r
13/18 * pi r is the general answer.