Nội dung text Conics Engg Question Bank Solution (HSC 26).pdf
2 Higher Math 2nd Paper Chapter-6 5. (3, – 1) Ges (1, – 1) Dc‡K›`a wewkó Dce„‡Ëi GKwU kxl©we›`y n‡Z Dc‡K›`a؇qi `~i‡Z¡i ̧Ydj 4 GKK n‡j Dce„‡Ëi mgxKiY wbY©q Ki| [BUET 21-22] mgvavb: Dce„ËwUi †K‡›`ai ̄’vbv1⁄4 3 + 1 2 – 1 (2 – 1) GLv‡b, cÖavb Aÿ x A‡ÿi mgvšÍivj Dc‡K›`a؇qi `~iZ¡, 2ae = 2 ae = 1 ...... (i) cÖkœg‡Z, (a – ae)(a + ae) = 4 a 2 – 1 2 = 4 a 2 = 5 Avgiv Rvwb, a 2 e 2 = a2 – b 2 b 2 = a2 – a 2 e 2 = 5 – 1 = 4 Dce„‡Ëi mgxKiY: (x – 2) 2 ( 5) 2 + (y + 1) 2 2 2 = 1 (x – 2) 2 5 + (y + 1) 2 4 = 1 (Ans.) 6. (1, 2) Dc‡K›`a, 2 Dr‡Kw›`aKZv Ges 2x + y = 1 wØKvÿwewkó KwY‡Ki mgxKiY wbY©q Ki| [BUET 20-21] mgvavb: KwY‡Ki mgxKiY, SP = e.PM (x – 1) 2 + (y – 2) 2 = 2 2x + y – 1 2 2 + 12 x 2 – 2x + 1 + y2 – 4y + 4 = 2 (2x + y – 1) 2 5 5x2 + 5y2 – 10x – 20y + 25 = 2(4x2 + y2 + 1 + 4xy – 2y – 4x) 3x2 – 3y2 + 8xy + 2x + 16y – 23 = 0 (Ans.) 7. GKwU Dce„‡Ëi mgxKiY wbY©q Ki, hvi Dc‡K‡›`ai ̄’vbv1⁄4 (0, 2), Dr‡Kw›`aKZv 1 2 Ges wbqvgK‡iLvi mgxKiY y + 4 = 0| Gi Dc‡Kw›`aK j‡¤^i •`N© ̈I wbY©q Ki| [BUET 19-20] mgvavb: (x – 0) 2 + (y – 2) 2 = 1 2 y + 4 1 x 2 + y2 + 4 – 4y = 1 4 (y2 + 16 + 8y) 4x2 + 4y2 – 16y + 16 = y2 + 8y + 16 4x2 + 3y2 – 24y = 0 4x2 + 3(y2 – 8y + 42 ) = 48 x 2 12 + (y – 4) 2 4 2 = 1 (Ans.); GLv‡b, 4 2 > 12 Dc‡Kw›`aK j‡¤^i •`N© ̈ = 2a2 b = 2 12 4 = 6 GKK (Ans.) 8. GKwU Dce„‡Ëi mgxKiY wbY©q Ki, hvi GKwU Dc‡K‡›`ai ̄’vbv1⁄4 (1, – 1), Abyiƒc w`Kvÿ x – y – 4 = 0 Ges hv (1, 1) we›`y w`‡q AwZμg K‡i| [BUET 17-18] mgvavb: Dce„‡Ëi mgxKiY, (x – 1)2 + (y + 1)2 = e2 (x – y – 4) 2 2 ; hv (1, 1) we›`yMvgx| (1 – 1)2 + (1 + 1)2 = e2 (1 – 1 – 4) 2 2 e 2 = 1 2 e = 1 2 mgxKiYwU, (x – 1)2 + (y + 1)2 = 1 2 (x – y – 4) 2 2 4x2 + 4y2 – 8x + 8y + 8 = x2 + y2 + 16 – 2xy – 8x + 8y 3x2 + 3y2 + 2xy – 8 = 0 (Ans.) 9. Ggb GKwU cive„‡Ëi mgxKiY wbY©q Ki hvi kxl©we›`y(4, – 3), Dc‡Kw›`aK j‡¤^i •`N© ̈ 4 Ges hvi Aÿ x A‡ÿi mgvšÍivj| [BUET 13-14; KUET 10-11; RUET 05-06; BUTex 04-05] mgvavb: GLv‡b, Dc‡Kw›`aK j‡¤^i •`N© ̈, |4a| = 4 4a = 4 Aÿ‡iLv x A‡ÿi mgvšÍivj Ges (4, – 3) kxl© wewkó cive„‡Ëi mgxKiY: (y + 3)2 = 4(x – 4) (Ans.) 10. GKwU Dce„‡Ëi AÿØq ̄’vbv‡1⁄4i AÿØq eivei Aew ̄’Z| Dce„ËwU x 9 + y 4 = 1 †iLv‡K x A‡ÿi Dci Ges x 2 + y 3 = 1 †iLv‡K y A‡ÿi Dci †Q` K‡i| Dce„ËwUi mgxKiY, Dr‡Kw›`aKZv Ges Dc‡K›`a `ywUi ̄’vbv1⁄4 wbY©q Ki| [BUET 11-12] mgvavb: Dce„‡Ëi, x A‡ÿi †Q`we›`y (9, 0) a = 9 y A‡ÿi †Q`we›`y (0, 3) b = 3 Dce„‡Ëi mgxKiY: x 2 9 2 + y 2 3 2 = 1 (Ans.) Dr‡Kw›`aKZv, e = 1 – b 2 a 2 = 1 – 3 2 9 2 = 72 9 (Ans.) Dc‡K›`a ( ae, 0) 9 72 9 0 ( 72 0) (Ans.) 11. 9x2 – 16y2 + 72x – 32y – 16 = 0 eμ‡iLvwUi cÖK...wZ, Zvi †K›`a I Dc‡K›`a؇qi ̄’vbv1⁄4, wbqvgK؇qi mgxKiY Ges bvwfj‡¤^i •`N© ̈ wbY©q Ki| [BUET 10-11] mgvavb: 9x2 – 16y2 + 72x – 32y – 16 = 0 9(x + 4)2 – 16(y + 1)2 = 144 (x + 4) 2 16 – (y + 1) 2 9 = 1 ...... (i) eμ‡iLvwU Awae„Ë| (Ans.) †K›`a n‡jv, (x + 4, y + 1) = 0 (x, y) (– 4, – 1) (Ans.) e = 16 + 9 16 = 5 4