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If the tangents AB and AQ are drawn from...

If the tangents AB and AQ are drawn from the point A(3, -1) to the circle `x^(2)+y^(2)-3x+2y-7=0` and C is the centre of circle, then the area of quadrilateral APCQ is :

A

9

B

4

C

2

D

non-existent

Text Solution

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The correct Answer is:
To solve the problem, we need to find the area of the quadrilateral APCQ, where A is the point from which the tangents are drawn to the circle defined by the equation \(x^2 + y^2 - 3x + 2y - 7 = 0\). ### Step 1: Find the center and radius of the circle The equation of the circle can be rewritten in standard form by completing the square. 1. Rearranging the equation: \[ x^2 - 3x + y^2 + 2y - 7 = 0 \] 2. Completing the square for \(x\): \[ x^2 - 3x = (x - \frac{3}{2})^2 - \frac{9}{4} \] 3. Completing the square for \(y\): \[ y^2 + 2y = (y + 1)^2 - 1 \] 4. Substitute back into the equation: \[ (x - \frac{3}{2})^2 - \frac{9}{4} + (y + 1)^2 - 1 - 7 = 0 \] \[ (x - \frac{3}{2})^2 + (y + 1)^2 = \frac{9}{4} + 1 + 7 = \frac{9}{4} + \frac{4}{4} + \frac{28}{4} = \frac{41}{4} \] Thus, the center \(C\) of the circle is \((\frac{3}{2}, -1)\) and the radius \(r\) is \(\sqrt{\frac{41}{4}} = \frac{\sqrt{41}}{2}\). ### Step 2: Calculate the length of the tangent from point A to the circle The formula for the length of the tangent from a point \(A(x_1, y_1)\) to a circle centered at \(C(h, k)\) with radius \(r\) is given by: \[ \text{Length of tangent} = \sqrt{(x_1 - h)^2 + (y_1 - k)^2 - r^2} \] Here, \(A(3, -1)\), \(C(\frac{3}{2}, -1)\), and \(r = \frac{\sqrt{41}}{2}\). 1. Calculate \(h\) and \(k\): \[ h = \frac{3}{2}, \quad k = -1 \] 2. Substitute into the formula: \[ \text{Length of tangent} = \sqrt{(3 - \frac{3}{2})^2 + (-1 + 1)^2 - \left(\frac{\sqrt{41}}{2}\right)^2} \] \[ = \sqrt{(\frac{3}{2})^2 + 0 - \frac{41}{4}} = \sqrt{\frac{9}{4} - \frac{41}{4}} = \sqrt{\frac{-32}{4}} = \sqrt{-8} \] Since the length of the tangent is imaginary, it indicates that point A lies inside the circle. ### Step 3: Conclusion about the area of quadrilateral APCQ Since the point A is inside the circle, no tangents can be drawn from A to the circle. Therefore, the area of quadrilateral APCQ does not exist. ### Final Answer The area of quadrilateral APCQ is **not defined**. ---
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