The distance to the focus and the distance directrix of the parabola are;
- Distance to the focus; √((x - 2)² + (y + 4)²)
- Distance to the directrix; |y + 6|
The steps used to find the distances to the focus and directrix are presented as follows;
The coordinate points on the parabola are; (2, -5), (0, -4), and (4, -4)
Therefore, we get the vertex form as follows;
y = a·(x - 2)² + (-5)
y = a·(x - 2)² - 5
When x = 0, we get;
-4 = a·(0 - 2)² - 5
a = 0.25
Therefore; y + 5 = 0.25·(x - 2)²
4×(y + 5) = (x - 2)²
p = 1
The coordinate of the focus is; (h, k + p) = (2, (-5) + 1)
(2, (-5) + 1) = (2, -4)
The focus is; (2, -4)
The directrix is; y = k - p, which is; y = -5 - 1
The directrix is; y = -6
Whereby the focus of the parabola with vertex at (2, -5) is the point (2, -4), and the directrix is the line y = -6, we get;
The distance of the point (x, y), from the
Distance to focus = √((x - 2)² + (y + 4)²)
Distance to directrix is; |y - (-6)| = |y + 6|