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Anil Kumar

· started a discussion

· 1 Months ago

equation solution not understand

Question:

ABC is a quarter circle and a smaller circle is inscribed in it. If AB = 1 cm., then find the radius of smaller circle. 

Options:
A)

( 2-1)    cm. 

B)

( 2+2   ) cm. 

C)

( 22-1)    cm. 

D)

 1- 22   cm

Solution:

Let, the radius of the inner smaller circle be ‘r’ and that of the outer quarter circle be R

  OB = R-r and BD = OD =r

  

In BDO,

By Pythagoras theorem

(R-r)2=r2+r2    . . . .. (i)

AB=R=1 cm   

1-2r+r2= 2r2 or r2+2r-1=0   

By solving quadratic equation, we get

r=(2-1)   

 The radius of smaller circle = 2-1 cm   

 

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