Dab tsi yog Directrix hauv parabola?
Dab tsi yog Directrix hauv parabola?

Video: Dab tsi yog Directrix hauv parabola?

Video: Dab tsi yog Directrix hauv parabola?
Video: What is a Chipset as Fast As Possible 2024, Kaum ib hlis
Anonim

Directrix . A parabola yog teem tag nrho cov ntsiab lus nyob rau hauv ib lub dav hlau uas yog ib tug sib npaug nrug deb ntawm ib tug muab point thiab muab kab. Lub ntsiab lus yog hu ua qhov tseem ceeb ntawm lub parabola , thiab kab yog hu ua directrix . Cov directrix yog perpendicular rau lub axis ntawm symmetry ntawm a parabola thiab tsis kov lub parabola.

Tsis tas li ntawd, koj yuav nrhiav tau Directrix ntawm parabola li cas?

Tus qauv qauv yog (x - h)2 = 4p (y - k), qhov kev tsom xam yog (h, k + p) thiab cov directrix yog y = k-p. Yog tias parabola yog rotated kom nws vertex yog (h, k) thiab nws axis ntawm symmetry yog parallel mus rau lub x-axis, nws muaj ib tug sib npaug ntawm (y - k)2 = 4p (x - h), qhov chaw tsom xam (h + p, k) thiab cov directrix yog x = h-p.

Tsis tas li ntawd, koj yuav pom daim ntawv vertex ntawm parabola li cas? f (x) = a(x - h)2 + k, qhov twg (h, k) yog qhov vertex ntawm parabola . FYI: Cov phau ntawv sib txawv muaj kev txhais lus sib txawv ntawm kev siv "tus qauv daim ntawv Ib txhia hais tias f (x) = ax2 + bx + c yog "standard daim ntawv ", thaum lwm tus hais tias f (x) = a(x - h)2 +k yog "standard daim ntawv ".

Ib yam li ntawd ib tug yuav nug, dab tsi yog Directrix ntawm ib tug hyperbola?

Hauv qhov xwm txheej ntawm a hyperbola , a directrix yog ib txoj kab ncaj nraim uas qhov kev ncua deb ntawm txhua qhov chaw ntawm lub hyperbola mus rau ib qho ntawm nws ob lub foci yog lub sij hawm ntawm qhov kev ncua deb ntawm mus rau qhov directrix , qhov twg yog qhov tsis tu ncua ntau dua. Nco ntsoov tias hyperbolas muaj ob foci thiab ob directrices, ib qho rau txhua qhov tsom.

Koj pom Directrix ntawm kev sib npaug li cas?

Tus qauv qauv yog (x - h)2 = 4p (y - k), qhov kev tsom xam yog (h, k + p) thiab cov directrix yog y = k-p. Yog hais tias lub parabola tig kom nws vertex yog (h, k) thiab nws axis ntawm symmetry yog parallel mus rau x-axis, nws muaj ib tug axis ntawm symmetry. kev sib npaug ntawm (y - k)2 = 4p (x - h), qhov chaw tsom xam (h + p, k) thiab cov directrix yog x = h-p.

Pom zoo: