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Question 320006
JEE Mathematics · Medium

Circle: Tangent equation MCQ

Solve this quality-checked JEE multiple-choice question, then review the correct answer and explanation.

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Tangent equationMediumQuestion 320006

Question

The equation of the tangent to x² + y² = r² at point (x₁, y₁) is:
  1. A
    xx₁ + yy₁ = r²
    Correct
  2. B
    x₁x + y₁y = r²
  3. C
    x/x₁ + y/y₁ = 1
  4. D
    x² + y² = r²

Correct answer

xx₁ + yy₁ = r²

Explanation

For circle x²+y²=r², tangent at (x₁,y₁): T = 0 → xx₁ + yy₁ = r². This is the T-formula.

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