Circle Theorem

This video is for the redesigned SAT which is for you if you are taking the SAT in March 2016 and beyond.

How to find the length of a line segment in a circle?

Circle Theorem - Basic Example

The sector of a circle shown above has center at point 0. The radius of the circle is, 5, and the length of the chord AB is 6. Line segment CO is perpendicular to line segment AB. What is the length, l, of the line segment CO?

(You could answer this question quicker if you could remember the Circle Theorem: A radius that is perpendicular to a chord bisects the chord.)

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