Question:

When the axes are rotated through an angle \( \theta \) about the origin in the anticlockwise direction and then translated to the new origin (2, -2), if the transformed equation of \( x^2+y^2=4 \) is \( X^2+Y^2+aX+bY+c=0 \), then \( a+b+c= \):

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When transforming equations due to translation, substitute new coordinates directly into the equation and simplify step by step.
Updated On: Jun 5, 2025
  • \( 4 \)
  • \( 8 \)
  • \( 0 \)
  • \( 12 \)
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The Correct Option is C

Solution and Explanation

The given equation \( x^2 + y^2 = 4 \) represents a circle centered at the origin with radius 2. Applying the transformation: - First, rotation does not affect the equation structurally. - Then, shifting the origin to (2, -2) results in replacing \( x \) and \( y \) with \( (X+2) \) and \( (Y-2) \). Expanding: \[ (X+2)^2 + (Y-2)^2 = 4 \] \[ X^2 + 4X + 4 + Y^2 - 4Y + 4 = 4 \] \[ X^2 + Y^2 + 4X - 4Y + 4 = 4 \] \[ X^2 + Y^2 + 4X - 4Y + 0 = 0 \] Thus, \( a = 4 \), \( b = -4 \), \( c = 0 \), and \( a + b + c = 0 \).
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