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Tangents. A line is tangent to a circle if it intersects the circle in exactly one point. This point is called the point of tangency. Consider the following diagram:. Theorem 10.9:. If a line is tangent to a circle, then it is perpendicular to the radius drawn to the point of tangency.
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A line is tangent to a circle if it intersects the circle in exactly one point. This point is called the point of tangency.
Theorem 10.9: • If a line is tangent to a circle, then it is perpendicular to the radius drawn to the point of tangency.
Example: If RT is tangent to Circle O, Then ORRT
Theorem 10.10: The converse of the last theorem is also true. This means: In a plane, if a line is perpendicular to a radius of a circle at the endpoint on the circle, then the line is a tangent of the circle. If ORRT, RT is tangent to Circle O
Theorem 10.11: • If two segments from the same exterior point are tangent to a circle, then the two segments are congruent. Example: ABCB
Example x+4 y 10 y-5
Circumscribed polygons: A polygon is circumscribed about a circle if each side of the polygon is tangent to the circle. • Example:
Example: Triangle HJK is circumscribed about circle G. Find the Perimeter of HJK if NK = JL+29. 45 JL + 29 18