Respuesta :

The parabola :
x² = 20 y
It is in the standard form : x² = 4 b y
b = 20 : 4 = 5
Vertex : ( 0, 0 );
Focus : ( 0, 5 );
Directrix :  y + 5 = 0;  y = - 5
Focal width:  4 * 5  = 20 units
Answer: A )

Answer:

Directrix is line with equation y=-5 and focus is the point with coordinates (0,5) with vertex (0,0) and focal width 20 units.

Step-by-step explanation:

Given the equation of parabola i.e

[tex]x^2=20y[/tex]

we have to find the vertex, focus, directrix, and focal width of the parabola.  

Parabola:  [tex]x^2=20y[/tex]

[tex]\text{standard equation of parabola}x^2=4by[/tex]

Comparing, we get

[tex]4b=20[/tex] ⇒ [tex]b=\frac{20}{4}=5[/tex]

Vertex: (0,0)

Focus: (0,b)=(0,5)

Directrix: y=-b ⇒ y=-5

Focal width:  4(5) = 20 units

Directrix is line with equation y=-5 and focus is the point with coordinates (0,5) with vertex (0,0) and focal width 20 units.