A tangent line to a circle intersects the circle at exactly one point on its circumference. The radius drawn from the center of the circle to the point of tangency is always perpendicular to the tangent line.
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There’s a special relationship between two secants that intersect outside of a circle. The length outside the circle, multiplied by the length of the whole secant is equal to the outside length of the other secant multiplied by the whole length of the other secant.
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