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Key Concepts
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1. Basic Terms
- Chord: A line segment joining any two points on the circle.
- Diameter: The longest chord passing through the center.
- Tangent: A line that touches the circle at exactly one point.
2. Tangent Properties
- The tangent at any point of a circle is perpendicular to the radius through the point of contact.
- The lengths of tangents drawn from an external point to a circle are equal.
3. Chords and Angles
- Equal chords of a circle subtend equal angles at the center.
- The perpendicular from the center of a circle to a chord bisects the chord.
- Angles in the same segment of a circle are equal.
- Angle in a semi-circle is a right angle (90°).