Find polar equation of a conic whose latus rectum is 2l and ecentricity e, the focus being the pole Share with your friends Share 1 Manbar Singh answered this Let S be the focus. Let ZM be the directrix of the conic.Draw SZ⊥to the directrix.Consider a point Pon the conic and let its polar coordinate be r, θ, so thatSP = r; ∠XSP = θLet LSL' be the latus rectum of length 2l, so thatsemi latus rectum, SL = lSince P is any point on the conic, then by the definition of conic,SP = e . PM = e . NZ = eSZ - SNNow, r = eSZ - eSN⇒r = eSZ - e SP cos θ⇒r = e SZ - er cos θ .....1But point L is also on the conic, sol = SL = e. LE = e. SZNow, from 1, we get r = l - er cos θ⇒r1 + e cos θ = l⇒lr = 1 + e cos θ 3 View Full Answer