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# Radii to Tangents - Concept

###### Brian McCall

###### Brian McCall

**Univ. of Wisconsin**

J.D. Univ. of Wisconsin Law school

Brian was a geometry teacher through the Teach for America program and started the geometry program at his school

When a radius is drawn to a point of tangency, the angle formed is always a right (90 degree) angle. This fact is commonly applied in problems with two tangent segments drawn to a circle from a point. If two **radii to tangents** are drawn in, a kite with two right angles is formed and the missing angles or sides can be found. Related topics include central angles, tangent segments to a circle, and chords.

When we have a tangent to a circle which means it's a line or line segment or even a ray that intersects the circle on only one point if we had to draw a radius to that point, something special happens. Over here I've written a tangent to a circle is and I left it blank purposely perpendicular to the radius drawn at the point of tangency so I can label this as a 90 degree angle. You're going to apply this in lots of different problems where you see a tangent in some form being drawn where it's connected to a radius.

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###### Brian McCall

B.S. in Chemical Engineering, University of Wisconsin

J.D. University of Wisconsin Law School (magna cum laude)

He doesn't beat around the bush. His straightforward teaching style is effective and his subtle midwestern accent is engaging. There's never a dull moment with him.

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