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Question

Question: The pole of the straight line \(x + 4y = 4\) with respect to ellipse \(x^{2} + 4y^{2} = 4\)is...

The pole of the straight line x+4y=4x + 4y = 4 with respect to ellipse x2+4y2=4x^{2} + 4y^{2} = 4is

A

(1, 4)

B

(1, 1)

C

(4, 1)

D

(4, 4)

Answer

(1, 1)

Explanation

Solution

Equation of polar of (x1,y1)(x_{1},y_{1}) w.r.t the ellipse is xx1+4yy1=4\mathbf{x}\mathbf{x}_{\mathbf{1}}\mathbf{+ 4y}\mathbf{y}_{\mathbf{1}}\mathbf{= 4}.....(i)

Comparing with x+4y=4x + 4y = 4 .....(ii)

x11=4y14=1\frac{x_{1}}{1} = \frac{4y_{1}}{4} = 1 \Rightarrow x1=1,y1=1x_{1} = 1,y_{1} = 1.

∴ Coordinates of pole (x1,y1)(x_{1},y_{1}) = (1, 1)