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Consider the circle x^(2) + y^(2) = 9 . ...

Consider the circle `x^(2) + y^(2) = 9` . Let P by any point lying on the positive x-axis. Tangents are drawn from this point to the given circle, meeting the Y-axis at `P_(1) and P_(2)` respectively. Then find the coordinates of point 'P' so that the area of the `DeltaPP_(1)P_(2)` is minimum.

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To solve the problem, we need to find the coordinates of point \( P \) on the positive x-axis such that the area of triangle \( \Delta P P_1 P_2 \) is minimized, where \( P_1 \) and \( P_2 \) are the points where the tangents from \( P \) touch the circle defined by the equation \( x^2 + y^2 = 9 \). ### Step-by-Step Solution: 1. **Identify the Circle and Point \( P \)**: The equation of the circle is \( x^2 + y^2 = 9 \). This circle has a center at \( (0, 0) \) and a radius \( r = 3 \). Let point \( P \) be \( (x, 0) \) on the positive x-axis. 2. **Use the Tangent Length Formula**: The length of the tangent from a point \( (x_1, y_1) \) to a circle with center \( (0, 0) \) and radius \( r \) is given by: \[ L = \sqrt{x_1^2 + y_1^2 - r^2} \] For point \( P = (x, 0) \): \[ L = \sqrt{x^2 + 0^2 - 9} = \sqrt{x^2 - 9} \] 3. **Coordinates of Points \( P_1 \) and \( P_2 \)**: The points \( P_1 \) and \( P_2 \) where the tangents touch the circle can be found using the angle \( \alpha \) that the radius makes with the x-axis. The coordinates of \( P_1 \) and \( P_2 \) can be expressed as: \[ P_1 = (0, y_1) \quad \text{and} \quad P_2 = (0, y_2) \] where \( y_1 = 3 \sin(\alpha) \) and \( y_2 = -3 \sin(\alpha) \). 4. **Area of Triangle \( \Delta P P_1 P_2 \)**: The area \( A \) of triangle \( \Delta P P_1 P_2 \) can be calculated using the formula: \[ A = \frac{1}{2} \times \text{Base} \times \text{Height} \] Here, the base \( P_1P_2 = 2 \times y_1 = 6 \sin(\alpha) \) and the height from \( P \) to the line \( P_1P_2 \) is \( OP = 3 \sec(\alpha) \). Therefore: \[ A = \frac{1}{2} \times 6 \sin(\alpha) \times 3 \sec(\alpha) = 9 \tan(\alpha) \] 5. **Minimizing the Area**: To minimize the area \( A = 9 \tan(\alpha) \), we need to find the maximum value of \( \tan(\alpha) \). The maximum value of \( \tan(\alpha) \) occurs when \( \alpha = \frac{\pi}{4} \), where \( \tan(\frac{\pi}{4}) = 1 \). 6. **Finding Coordinates of Point \( P \)**: Substituting \( \alpha = \frac{\pi}{4} \): \[ OP = 3 \sec\left(\frac{\pi}{4}\right) = 3 \cdot \sqrt{2} \] Therefore, the coordinates of point \( P \) are: \[ P = (3\sqrt{2}, 0) \] ### Final Answer: The coordinates of point \( P \) are \( (3\sqrt{2}, 0) \).
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