Find the standard form of the equation of the parabola with a focus at (0, 8) and a directrix at y = -8.

y = one divided by thirty twox2
y2 = 8x
y2 = 32x
y = one divided by eightx2

Respuesta :

Answer:

The standard form of the equation of the parabola will be [tex]y=\frac{x^2}{32}[/tex].

Step-by-step explanation:

To find he equation of the parabola with a focus at (0, 8) and

a directrix at y = -8, we may use the distance formula.

[tex]\sqrt{\left(x-0\right)^2+\left(y-8\right)^2}=\sqrt{\left(x-x\right)^2+\left(y+8\right)^2}[/tex]

[tex]\mathrm{Square\:both\:sides}[/tex]

[tex]\left(\sqrt{\left(x-0\right)^2+\left(y-8\right)^2}\right)^2=\left(\sqrt{\left(x-x\right)^2+\left(y+8\right)^2}\right)^2[/tex]  [tex]......A[/tex]

Solving

[tex]\left(\sqrt{\left(x-0\right)^2+\left(y-8\right)^2}\right)^2[/tex]

[tex]\mathrm{Apply\:radical\:rule}:\quad \sqrt{a}=a^{\frac{1}{2}}[/tex]

[tex]=\left(\left(\left(x-0\right)^2+\left(y-8\right)^2\right)^{\frac{1}{2}}\right)^2[/tex]

[tex]\mathrm{Apply\:exponent\:rule}:\quad \left(a^b\right)^c=a^{bc}[/tex]

[tex]=\left(\left(x-0\right)^2+\left(y-8\right)^2\right)^{\frac{1}{2}\cdot \:2}[/tex]

[tex]=\left(x-0\right)^2+\left(y-8\right)^2[/tex]           ∵ [tex]\frac{1}{2}\cdot \:2=1[/tex]

[tex]=x^2+y^2-16y+64[/tex]    ∵ [tex]\mathrm{Expand\:}\left(x-0\right)^2+\left(y-8\right)^2:\quad x^2+y^2-16y+64[/tex]

Similarly

[tex]\mathrm{Expand\:}\left(\sqrt{\left(x-x\right)^2+\left(y+8\right)^2}\right)^2:\quad \left(y+8\right)^2[/tex]

So, the equation A becomes

[tex]x^2+y^2-16y+64=\left(y+8\right)^2[/tex]

[tex]x^2+y^2-16y+64=y^2+16y+64[/tex]

[tex]y^2-16y=y^2+16y-x^2[/tex]

[tex]-32y=-x^2[/tex]

[tex]\frac{-32y}{-32}=\frac{-x^2}{-32}[/tex]

[tex]y=\frac{x^2}{32}[/tex]

Therefor, the standard form of the equation of the parabola will be [tex]y=\frac{x^2}{32}[/tex].