Circles
Gujarat Board · Class 9 · Mathematics
Flashcards for Circles — Gujarat Board Class 9 Mathematics. Quick Q&A cards covering key concepts, definitions, and formulas.
What is the angle subtended by a chord PQ at point R?
Answer
The angle subtended by chord PQ at point R is ∠PRQ, formed by joining point R to both endpoints P and Q of the chord. If R is at the center, it's called the angle subtended at the center. If R is on t
State Theorem 9.1 about equal chords and angles at center.
Answer
Theorem 9.1: Equal chords of a circle subtend equal angles at the centre. This means if two chords AB and CD are equal in length, then ∠AOB = ∠COD, where O is the center of the circle.
What is the converse of Theorem 9.1?
Answer
Theorem 9.2: If the angles subtended by chords of a circle at the centre are equal, then the chords are equal. This means if ∠AOB = ∠COD, then chord AB = chord CD.
State Theorem 9.3 about perpendicular from center to chord.
Answer
Theorem 9.3: The perpendicular from the centre of a circle to a chord bisects the chord. If OM ⊥ AB where O is center and M is on chord AB, then AM = MB.
What is the converse of Theorem 9.3?
Answer
Theorem 9.4: The line drawn through the centre of a circle to bisect a chord is perpendicular to the chord. If OM bisects chord AB, then OM ⊥ AB.
How is the distance of a line from a point defined?
Answer
The distance of a line from a point is the length of the perpendicular from the point to the line. This perpendicular is the shortest distance between the point and the line. If the point lies on the
State Theorem 9.5 about equal chords and their distances from center.
Answer
Theorem 9.5: Equal chords of a circle (or of congruent circles) are equidistant from the centre (or centres). If AB = CD, then the perpendicular distances from center O to both chords are equal.
What is the converse of Theorem 9.5?
Answer
Theorem 9.6: Chords equidistant from the centre of a circle are equal in length. If two chords are at the same perpendicular distance from the center, then the chords are equal.
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What are the important topics in Circles for Gujarat Board Class 9 Mathematics?
Circles covers several key topics that are frequently asked in Gujarat Board Class 9 board exams. Focus on the core concepts listed on this page and practise related questions to build confidence.
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There are 20 flashcards for Circles covering key definitions, formulas, and concepts. Use them daily for 10–15 minutes for best results.
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