NCERT Class 9 Solutions: Circles (Chapter 10) Exercise 10.3 – Part 1
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Radius, Diameter Chord, Tangent and Secant
Q-1 Draw different pairs of circles. How many points does each pair have in common? What is the maximum number of common points?
Solution:
No common point.
Outer and Inner Circles Which Have No Common Point
No point common
Two Circle That Center Point O and O'
One point P is common
Circles Which Have a Single Common Point
One point P is common
Outer and Inner Circles Which Have a Single Common Point
Two point P and Q are common
Circles Which Have a 2 Common Points
Infinite number of common points between two congruent and overlapping circles
Two Congruent and Overlapping Circles with Infinite Common Points
Therefore there can be infinite such points
Q-2 Suppose you are given a circle. Give a construction to find its centre.
Solution:
Circle with Center at A
Key idea: The key idea for solving this problems is to realize that the perpendicular bisector of chords of the circle pass through the center. So if we draw two perpendicular bisectors of two distinct chords they will intersect at the center of the circle. (The line joining the center and perpendicular to the chord, bisects the chord)
Following steps can be used to complete the construction:
Step 1 : Drawn the circle
Step 2 : EF and GH are two chords
Step 3: Draw the perpendicular bisectors of the chords EF and GH.
The point of intersection of two perpendicular bisector is the center of the circle.