CircleHard

Question

The equation of the tangents from the origin to the circle x2 + y2 + 2rx + 2hy + h2 = 0, are

Options

A.x = 0
B.y = 0
C.(h2 - r2)x - 2rhy = 0
D.(h2 - r2)x + 2rhy = 0

Solution

       
Since, thangents are drawn form origin. So, the equation of tangent by y = mx.
⇒     Length of perpendicular from origin = radius
⇒    
⇒     m2r2 + h2 + 2mrh = r2 (m2 + 1)
⇒    
∴     Equation of tangents are
Therefore a, c are the answers.

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