another conics question (geez i hate this topic) (1 Viewer)

[dawso]

P (a cos @, b sin @) and Q (a cos &, b sin &) lie on ellipse (insert ellipse equation here), if PQ subtends a right angle at (a, 0), show that:

tan (@/2) tan (&/2) = - b^2/a^2

cheers peoples...

 

[shafqat]

let (a,0) be O
find gradient of PO, PQ
gradient(PO) * gradient (PQ) = -1

 

[shafqat]

i think t formula may be useful once you get that expression
just try trig bashing