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Class Nine Mathematics Chap 10 extra Ques-answers

# Chapter 10 : Circles

Very Short Answer Type Questions: [1 Mark]

1. Which is the longest chord of the circle?

Sol. Diameter is the longest chord of the circle.

2. What is another name of the perimeter of a circle?

Sol. The perimeter of a circle is also known as the circumference of the circle.

3. If chords of a circle (or of congruent circles) are equal then angle subtend at the centre by them will be equal? Is, it true or false?

Sol. True

4. If two chords of a circle subtend equal angles at the centre, what will be the relationship between them?

Sol. Both the chords will be equal.

5. What is the minimum number of points required to determine a unique circle?

Sol. Minimum 3 points are required to determine a unique circle.

6. How many circles can be drawn from three non-collinear points?

Sol. One and only one circle can be drawn from three non-collinear points.

7. What is the relationship between the chord of a circle and perpendicular to it from the centre?

Sol. A perpendicular line from the centre bisects the chord.

8. Two chords AB and CD of a circle are each at a distance 4 cm from the centre. Then Prove that AB = CD.

Sol. We know that the chords which are equidistant from the centre of the circle are equal in length.

AB = CD

• In the given figure, O is the centre of the circle. If OA = 5 cm and OC = 3 cm, then find the length of AB.

Sol.

AB = 2 × AC = 2 × 4 cm = 8 cm.