



 
Hi Rachel, Here is my diagram, $K$ is the center of the circle and $D$ is the point where the line segments $AC$ and $BK$ intersect.The first step is to show that the angle $BDA$ is a right angle and hence that $D$ is the midpoint of $CA.$ Can you see how to do this? This also ensures that angle $KDC$ is a right angle. Let the radius of the circle be $x$ cm. Since angle $BDA$ is a right angle $BD$ is the height of the triangle $ABC$ and hence $BD = 5 \mbox{ cm.}$ What is the length $DK?$ What does Pythagoras theorem tell you about the right triangle $KDC?$ Solve for $x.$ Penny  


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