2010 AMC 10B Problems/Problem 6

Assuming the reader is not readily capable to understand how will always be right, the I will continue with an easily understandable solution. Since is the center, are all radii, they are congruent. Thus, and are isosceles triangles. Also, note that and are supplementary, then $\angle COA = 180 - 50 = 130 \degrees$ (Error compiling LaTeX. Unknown error_msg). Since is isosceles, then . They also sum to $50 \degrees$ (Error compiling LaTeX. Unknown error_msg), so each angle is $\boxed{\mathrm{(B)} 25 \degrees}$ (Error compiling LaTeX. Unknown error_msg).