Question

The radius of a circle is 20 cm. It is divided into four parts of equal area by drawing three concentric circles inside it. Then, the radius of the largest of three concentric circles drawn is:
(a) 10√5 cm
(b) 10√3 cm
(c) 10 cm
(d) 10√2 cm



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Answer 1

Answer:

b) 10√3 cm

Step-by-step explanation:

Suppose r is the radius of the largest of the three circles

∴ area of the largest circle =  3/4 × area of given circle

We have

πr ^2  = 3/4×pi×(20)^2

r ^2   = 3/4×20×20  =300

r=  √300 =10√3 cm

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cm