Other Angle Relationships Section 10.6

Tangent-Chord Theorem If a tangent and a chord intersect at a point on a circle, then the measure of each angle formed is one half the measure of its intercepted arc.

Example 1

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Example 2

Interior Intersection Theorem If two chords intersect in the interior of a circle, then the measure of each angle is one half the sum of the measures of the arcs intercepted by the angle and its vertical angle.

Exterior Intersection Theorem If a tangent and a secant, two tangents, or two secants intersect in the exterior of a circle, then the measure of the angle formed is one half the difference of the measures of the intercepted arcs.

Diagrams for Exterior Intersection Theorem

Example 3 Find the value of x.

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Example 4 Find the value of x.

Example 5 Find the value of x.

Chord Product Theorem If two chords intersect in the interior of a circle, then the product of the lengths of the segments of one chord is equal to the product of the lengths of the segments of the other chord.

Example 1 Find the value of x.

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Secant-Secant Theorem If two secant segments share the same endpoint outside a circle, then the product of the length of one secant segment and the length of its external segment equals the product of the length of the other secant segment and the length of its external segment.

Secant-Tangent Theorem If a secant segment and a tangent segment share an endpoint outside a circle, then the product of the length of the secant segment and the length of its external segment equals the square of the length of the tangent segment.

Example 2 Find the value of x.

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Example 3 Find the value of x.

Try This! Find the value of x.