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The point (1,2) lies inside the circle ...

The point (1,2) lies inside the circle `x^(2)+y^(2)-2x+6y+1=0`

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To determine whether the point (1, 2) lies inside the circle given by the equation \(x^2 + y^2 - 2x + 6y + 1 = 0\), we can follow these steps: ### Step 1: Rewrite the Circle Equation First, we can rewrite the equation of the circle in a more standard form. The given equation is: \[ x^2 + y^2 - 2x + 6y + 1 = 0 \] We can rearrange it to: \[ x^2 - 2x + y^2 + 6y + 1 = 0 \] ### Step 2: Complete the Square Next, we complete the square for both \(x\) and \(y\). For \(x\): \[ x^2 - 2x = (x - 1)^2 - 1 \] For \(y\): \[ y^2 + 6y = (y + 3)^2 - 9 \] Substituting these back into the equation gives: \[ (x - 1)^2 - 1 + (y + 3)^2 - 9 + 1 = 0 \] Simplifying this: \[ (x - 1)^2 + (y + 3)^2 - 9 = 0 \] Thus, we can rewrite it as: \[ (x - 1)^2 + (y + 3)^2 = 9 \] ### Step 3: Identify the Circle's Center and Radius From the equation \((x - 1)^2 + (y + 3)^2 = 9\), we can identify: - The center of the circle is at \((1, -3)\). - The radius of the circle is \(3\) (since \(9 = 3^2\)). ### Step 4: Calculate the Distance from the Point to the Center Now, we need to find the distance from the point \((1, 2)\) to the center \((1, -3)\). The distance \(d\) can be calculated using the distance formula: \[ d = \sqrt{(x_2 - x_1)^2 + (y_2 - y_1)^2} \] Substituting in our points: \[ d = \sqrt{(1 - 1)^2 + (2 - (-3))^2} = \sqrt{0 + (2 + 3)^2} = \sqrt{5^2} = 5 \] ### Step 5: Compare the Distance with the Radius Now we compare the distance \(d\) with the radius \(r\): - The distance \(d = 5\) - The radius \(r = 3\) Since \(d > r\), the point \((1, 2)\) lies outside the circle. ### Conclusion Thus, the statement that the point \((1, 2)\) lies inside the circle is false. ---
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Knowledge Check

  • The point (2, 4) lies inside the circle x^(2) + y^(2) = 16 . The above statement is

    A
    Always false
    B
    Always true
    C
    Can be true
    D
    Cannot be determined
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    A
    `|alpha|ltsqrt(3)`
    B
    `|alpha|lt2`
    C
    `(1)/(4)ltalphaltsqrt(3)`
    D
    none of these
  • The tangent to the circle x^(2)+y^(2)=5 at the point (1, - 2) also touches the circle x^(2) +y^(2) -8x +6y +20 =0 at

    A
    (-2, 1)
    B
    (-3, 0)
    C
    (-1, -1)
    D
    (3, -1)
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