14.5 Tangents to Circles and Spheres

Definition: Tangent

A line that intersectsthe circle in exactlyone point.

Real ­ life examples of tangency points:

Radius ­ Tangent Theorem:

A line is tangent to a circle iff it's       tothe radius at its endpoint on the circle.

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Tangent to Sphere:A line or a plane that intersectsthe sphere in exactly one point.

2. Assume the radius of the earth is 3,969 miles or 6,375 kilometers and that there are no hills or obstructions.

How many miles would a person be able to see from the roof of the Sears Tower in Chicago at 1,454 feet?

2. Assume the radius of the earth is 3,969 miles or 6,375 kilometers and that there are no hills or obstructions.

How many miles would a person be able to see from the top of Mt. Everest, which has a height of 29,028 feet?