Q1 of 31 Page 65

The length of a radius of a circle with its centre O is 5 cm. and the length of its chord AB is 8 cm. Let us write by calculating, the distance of the chord AB from the centre O.


Given radius = 5cm, AB = 5cm


Perpendicular from the center of the circle to any Chord bisects it in two line segments



So, AD = BD


In ODB


OB = 5cm


BD = 4cm


Using Pythagoras Theorem


base2 + Height2 = Hypotenuse2


⇒ OD2 + DB2 = OB2


⇒ OD2 = 25-16


⇒ OD2 = 9


⇒ OD = 3cm


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Let us write true or false:

i. The circle is a plane figure.


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iii. The Sector is a plane region.


iv. The chord is a line segment


v. The arc is a line segment.


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vii. One and only one circle can be drawn by taking a fixed point as its centre.


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