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What is the area common to the circles r = a and r = 2a cos θ? 
  • a)
    0.524 a2    
  • b)
    0.614 a2  
  • c)
    1.047 a2    
  • d)
    1.228 a2  
Correct answer is option 'D'. Can you explain this answer?
Verified Answer
What is the area common to the circles r = a and r = 2a cos θ?a)0...
Area common to circles r = a  
And r = 2a cos θ is 1.228 a2
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What is the area common to the circles r = a and r = 2a cos θ?a)0...
Solution:

Step 1: Find the intersection points of the two circles.

The equation of the first circle is r = a, and the equation of the second circle is r = 2a cosθ. We can find the intersection points by setting the two equations equal to each other and solving for θ.

a = 2a cosθ
cosθ = 1/2
θ = π/3, 5π/3

Step 2: Find the area of the common region.

The area of the common region can be found by subtracting the area of the sector between θ = π/3 and θ = 5π/3 from the area of the triangle formed by the two intersection points and the origin.

Area of sector = (θ/2)r^2 = (2π/3)(a^2) = (2/3)πa^2
Area of triangle = (1/2)(2a)(a sinπ/3) = (1/2)(2a)(a√3/2) = √3a^2/2

Area of common region = Area of sector - Area of triangle
= (2/3)πa^2 - √3a^2/2
= 0.616a^2

Therefore, the correct answer is option (D) 1.228a^2.
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Community Answer
What is the area common to the circles r = a and r = 2a cos θ?a)0...
A=2aCos@
@=π/3
Area= ( 0 to π/3 integration of a^2 d@ ) + ( π/3 to π/2 integration of 4a^2 Cos^2(@) d@)
Area= ( 2.094a^2 ) - ( 0.866a^2 )
Area= 1.228a^2
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What is the area common to the circles r = a and r = 2a cos θ?a)0.524 a2 b)0.614 a2 c)1.047 a2 d)1.228 a2 Correct answer is option 'D'. Can you explain this answer?
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