Q.

AB is one of the direct common tangent of two circles of radii 12 cm and 4 cm respectively touching each other. Find the area of the region enclosed by the circles and the tangent.


     Question Image

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a

24.78 c m 2  

b

18.53 c m 2  

c

19.54 c m 2  

d

14.8 c m 2   

answer is B.

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Detailed Solution

It is given that the radii of two circles are PA=12cm and QB=4cm.
We have to find the area of the shaded region.
The area of a sector can be expressed as, A= θ 360 ° π r 2   . Here r   is the radius of a circle.
The required figure geometry is shown below,
     Question Image Then, by using the Pythagoras theorem from figure geometry,
     P Q 2 =P R 2 +R Q 2 16 2 = 8 2 +R Q 2 R Q 2 =192 RQ=8 3 cm   
The area of a trapezium, PABQ,
A= 1 2 AB PA+QB A= 1 2 8 3 12+4 A=64 3 cm    In the triangle PQR,   Q= 180 ° P   
Q= 180 ° 60 °     
Q= 120 °  
Thus, the area of the region enclosed by the circles and the tangent isQuestion ImageThe required area is Question Image cm 2  .
Therefore, the correct option is 2.
 
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AB is one of the direct common tangent of two circles of radii 12 cm and 4 cm respectively touching each other. Find the area of the region enclosed by the circles and the tangent.