Maths-

#### PQ and QR are two focal chords of an ellipse and the eccentric angles of P,Q,R and

*, *respectively then tan tan is equal to -

Maths-General

- cot
- cot
^{2}
- None of these
- 2 cot

^{2}#### Answer:The correct answer is: cot^{2}

P (a cos 2 , b sin 2 ), Q (a cos 2 , b sin 2 )

R (a cos 2 , b sin 2 )

chord's PQ equation

cos ( + ) + sin ( + ) = cos ( – )

PQ passes through the focus (ae, 0)

e =

PR passes through the focus (– ae, 0) the

– e =

= –

Apply componendo and dividendo, we get

=

=

tan tan = cot^{2}

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=

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Two curves are symmetrical about both axes and intersect in four points, so, the circle through their points of intersection will have centre at origin.

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maths-General

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e =

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Let P(4 cos , 3 sin ) and Q (4 cos , 3 sin ) be a focal chord of the ellipse passing through the focus at (, 0).

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=

=

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=

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