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Find the pole of the straight line 9 ...

Find the pole of the straight line
` 9 x + y - 28 = 0 …………(1)`
with respect to the circle
` 2 x^(2) + 2y^(2) - 3x + 5y - 7 = 0 ………….(2)`

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To find the pole of the straight line \( 9x + y - 28 = 0 \) with respect to the circle \( 2x^2 + 2y^2 - 3x + 5y - 7 = 0 \), we follow these steps: ### Step 1: Rewrite the circle equation in standard form The given circle equation is: \[ 2x^2 + 2y^2 - 3x + 5y - 7 = 0 \] We can divide the entire equation by 2 to simplify it: \[ x^2 + y^2 - \frac{3}{2}x + \frac{5}{2}y - \frac{7}{2} = 0 \] ### Step 2: Identify the coefficients The standard form of a circle is: \[ x^2 + y^2 + 2gx + 2fy + c = 0 \] From our equation, we can identify: - \( 2g = -\frac{3}{2} \) → \( g = -\frac{3}{4} \) - \( 2f = \frac{5}{2} \) → \( f = \frac{5}{4} \) - \( c = -\frac{7}{2} \) ### Step 3: Set up the polar equation The polar equation of a point \( (h, k) \) with respect to the circle is given by: \[ xh + yk + g(x^2 + y^2) + f(x + y) + c = 0 \] Substituting \( g \), \( f \), and \( c \) into the polar equation, we have: \[ xh + yk - \frac{3}{4}(x^2 + y^2) + \frac{5}{4}(x + y) - \frac{7}{2} = 0 \] ### Step 4: Substitute the line equation We need to express the line \( 9x + y - 28 = 0 \) in terms of \( h \) and \( k \): \[ 9x + y = 28 \] This means \( y = 28 - 9x \). ### Step 5: Equate coefficients We can equate the coefficients of \( x \) and \( y \) from the polar equation and the line equation. The polar equation can be simplified to: \[ xh + yk - \frac{3}{4}x^2 - \frac{3}{4}y^2 + \frac{5}{4}x + \frac{5}{4}y - \frac{7}{2} = 0 \] Comparing coefficients with \( 9x + y - 28 = 0 \): 1. Coefficient of \( x \): \( h - \frac{3}{4} = 9 \) 2. Coefficient of \( y \): \( k + \frac{5}{4} = 1 \) 3. Constant term: \( -\frac{7}{2} = -28 \) ### Step 6: Solve for \( h \) and \( k \) From the first equation: \[ h - \frac{3}{4} = 9 \implies h = 9 + \frac{3}{4} = \frac{36}{4} + \frac{3}{4} = \frac{39}{4} \] From the second equation: \[ k + \frac{5}{4} = 1 \implies k = 1 - \frac{5}{4} = \frac{4}{4} - \frac{5}{4} = -\frac{1}{4} \] ### Step 7: Final result Thus, the coordinates of the pole \( (h, k) \) are: \[ \left( \frac{39}{4}, -\frac{1}{4} \right) \]
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