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The circle to which two tangents can be ...

The circle to which two tangents can be drawn from origin is

A

`x^(2)+y^(2)-8x-4y-3=0`

B

`x^(2)+y^(2)+4x+2y+2=0`

C

`x^(2)+y^(2)-8x+6y+1=0`

D

Both 2 and 3

Text Solution

AI Generated Solution

The correct Answer is:
To determine the circle to which two tangents can be drawn from the origin, we will analyze the given equations of circles step by step. ### Step 1: Understand the Circle Equation The general equation of a circle is given by: \[ x^2 + y^2 + 2gx + 2fy + c = 0 \] From this equation, we can identify the center of the circle as \((-g, -f)\) and the radius \(r\) can be calculated using: \[ r = \sqrt{g^2 + f^2 - c} \] ### Step 2: Analyze the First Circle The first circle is given by: \[ x^2 + y^2 - 8x - 4y - 3 = 0 \] **Identify g, f, and c:** - \(g = -8\) - \(f = -4\) - \(c = -3\) **Calculate the center and radius:** - Center: \((4, 2)\) (since \(-g, -f\)) - Radius: \[ r = \sqrt{(-8)^2 + (-4)^2 - (-3)} = \sqrt{64 + 16 + 3} = \sqrt{83} \] **Calculate distance from origin to center (OC):** \[ OC = \sqrt{4^2 + 2^2} = \sqrt{16 + 4} = \sqrt{20} \] **Check the condition for tangents:** Since \(OC < r\) (i.e., \(\sqrt{20} < \sqrt{83}\)), there are no tangents from the origin to this circle. ### Step 3: Analyze the Second Circle The second circle is given by: \[ x^2 + y^2 + 4x + 2y - 2 = 0 \] **Identify g, f, and c:** - \(g = 4\) - \(f = 2\) - \(c = -2\) **Calculate the center and radius:** - Center: \((-4, -2)\) - Radius: \[ r = \sqrt{(4)^2 + (2)^2 - (-2)} = \sqrt{16 + 4 + 2} = \sqrt{22} \] **Calculate distance from origin to center (OC):** \[ OC = \sqrt{(-4)^2 + (-2)^2} = \sqrt{16 + 4} = \sqrt{20} \] **Check the condition for tangents:** Since \(OC > r\) (i.e., \(\sqrt{20} > \sqrt{22}\)), there are two tangents from the origin to this circle. ### Step 4: Analyze the Third Circle The third circle is given by: \[ x^2 + y^2 - 8x + 6y - 1 = 0 \] **Identify g, f, and c:** - \(g = -8\) - \(f = 6\) - \(c = -1\) **Calculate the center and radius:** - Center: \((4, -3)\) - Radius: \[ r = \sqrt{(-8)^2 + (6)^2 - (-1)} = \sqrt{64 + 36 + 1} = \sqrt{101} \] **Calculate distance from origin to center (OC):** \[ OC = \sqrt{(4)^2 + (-3)^2} = \sqrt{16 + 9} = \sqrt{25} = 5 \] **Check the condition for tangents:** Since \(OC > r\) (i.e., \(5 > \sqrt{101}\)), there are two tangents from the origin to this circle. ### Conclusion From the analysis, the circles from the second and third equations allow for two tangents to be drawn from the origin. ### Final Answer The circles to which two tangents can be drawn from the origin are the second and third circles.
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