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).