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There are 2 circles passing through poin...

There are 2 circles passing through points A(-1, 2) and B(2, 3) having radius `sqrt(5)`. Then the length of intercept on axis of the circle intersecting x-axis is :

A

2

B

3

C

4

D

5

Text Solution

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The correct Answer is:
To solve the problem, we need to find the length of the intercept on the x-axis of the circle that passes through the points A(-1, 2) and B(2, 3) with a radius of \(\sqrt{5}\). ### Step-by-Step Solution: 1. **Identify the center of the circle**: Let the center of the circle be \(C(a, b)\). The distances from the center to points A and B must equal the radius \(\sqrt{5}\). 2. **Set up the equations based on the distances**: The distance \(CA\) can be expressed as: \[ CA^2 = (a + 1)^2 + (b - 2)^2 = 5 \] The distance \(CB\) can be expressed as: \[ CB^2 = (a - 2)^2 + (b - 3)^2 = 5 \] 3. **Expand both equations**: Expanding the first equation: \[ (a + 1)^2 + (b - 2)^2 = 5 \implies a^2 + 2a + 1 + b^2 - 4b + 4 = 5 \implies a^2 + b^2 + 2a - 4b = 0 \quad \text{(Equation 1)} \] Expanding the second equation: \[ (a - 2)^2 + (b - 3)^2 = 5 \implies a^2 - 4a + 4 + b^2 - 6b + 9 = 5 \implies a^2 + b^2 - 4a - 6b + 8 = 0 \quad \text{(Equation 2)} \] 4. **Subtract Equation 1 from Equation 2**: \[ (a^2 + b^2 - 4a - 6b + 8) - (a^2 + b^2 + 2a - 4b) = 0 \] This simplifies to: \[ -6a - 2b + 8 + 4 = 0 \implies -6a - 2b + 12 = 0 \implies 3a + b = 6 \quad \text{(Equation 3)} \] 5. **Substitute Equation 3 into Equation 1**: From Equation 3, we can express \(b\) in terms of \(a\): \[ b = 6 - 3a \] Substituting into Equation 1: \[ a^2 + (6 - 3a)^2 + 2a - 4(6 - 3a) = 0 \] Expanding this gives: \[ a^2 + (36 - 36a + 9a^2) + 2a - 24 + 12a = 0 \] Simplifying: \[ 10a^2 - 22a + 12 = 0 \] 6. **Solve the quadratic equation**: Using the quadratic formula: \[ a = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} = \frac{22 \pm \sqrt{(-22)^2 - 4 \cdot 10 \cdot 12}}{2 \cdot 10} \] \[ = \frac{22 \pm \sqrt{484 - 480}}{20} = \frac{22 \pm 2}{20} \] This gives: \[ a = \frac{24}{20} = 1.2 \quad \text{or} \quad a = \frac{20}{20} = 1 \] 7. **Find corresponding values of \(b\)**: For \(a = 1.2\): \[ b = 6 - 3(1.2) = 2.4 \] For \(a = 1\): \[ b = 6 - 3(1) = 3 \] 8. **Determine the equations of the circles**: The centers are \(C(1.2, 2.4)\) and \(C(1, 3)\). The equations of the circles are: \[ (x - 1.2)^2 + (y - 2.4)^2 = 5 \quad \text{and} \quad (x - 1)^2 + (y - 3)^2 = 5 \] 9. **Find the x-intercepts**: Set \(y = 0\) in both equations and solve for \(x\): For the first circle: \[ (x - 1.2)^2 + (0 - 2.4)^2 = 5 \implies (x - 1.2)^2 + 5.76 = 5 \implies (x - 1.2)^2 = -0.76 \quad \text{(no real solution)} \] For the second circle: \[ (x - 1)^2 + (0 - 3)^2 = 5 \implies (x - 1)^2 + 9 = 5 \implies (x - 1)^2 = -4 \quad \text{(no real solution)} \] 10. **Conclusion**: Since both circles do not intersect the x-axis, the length of the intercept on the x-axis is \(0\). ### Final Answer: The length of the intercept on the x-axis of the circle intersecting the x-axis is \(0\).
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