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The length of tangent from an external p...

The length of tangent from an external point on a circle is always greater than the radius of the circle.

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To solve the question, we need to analyze the statement: "The length of the tangent from an external point on a circle is always greater than the radius of the circle." ### Step-by-Step Solution: 1. **Understanding the Circle and Tangent**: - Let’s denote the center of the circle as point O and the radius of the circle as r. - An external point P is located outside the circle. 2. **Drawing the Tangent**: - From point P, we can draw a tangent line that touches the circle at point A. - By definition, a tangent to a circle is a line that touches the circle at exactly one point. 3. **Identifying the Radius**: - The radius OA is the line segment from the center O to the point A where the tangent touches the circle. 4. **Applying the Pythagorean Theorem**: - In triangle OAP, we can apply the Pythagorean theorem because OA is perpendicular to the tangent PA at point A. - According to the theorem: \[ OP^2 = OA^2 + AP^2 \] - Here, OP is the distance from the external point P to the center O, OA is the radius (r), and AP is the length of the tangent from point P to point A. 5. **Analyzing the Relationship**: - Rearranging the equation gives: \[ AP^2 = OP^2 - OA^2 \] - Since OP is greater than OA (because P is an external point), it follows that: \[ AP^2 > 0 \quad \text{(because OP > OA)} \] - Thus, \( AP \) must be greater than 0, but we need to compare it to the radius. 6. **Considering Different Positions of P**: - If point P is very far from the circle, the length of the tangent PA will be greater than the radius OA. - If point P is very close to the circle, the length of the tangent PA can approach the radius OA but will never be less than it. 7. **Conclusion**: - Therefore, the statement "the length of tangent from an external point on a circle is always greater than the radius of the circle" is **false**. The length of the tangent can be equal to or greater than the radius depending on the position of point P.
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