Maths-

General

Easy

Question

# 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 -

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

^{2}## 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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