Which equation represents a parabola that has a focus of (0 0) and a directrix of y = 2
2 answers:
Answer:
4.
Step-by-step explanation:
Given,
Focus of parabola = (0,0)
And, directrix is, y = 2,
Thus, the parabola must be along y-axis,
We know that,
The standard form of a parabola along y-axis,
Where, focus = (h, k+p)
And, directrix, y = k-p
Thus, we can write,
h = 0, k+p = 0
k-p = 2
⇒ k+p + k-p = 0 + 2
⇒ 2k = 2 ⇒ k = 1
⇒ 1 - p = 2 ⇒ p = - 1
Hence, the equation of the parabola is,
Option 4 is correct.
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Answer: All three of the altitudes lie entirely outside the triangle.
Step-by-step explanation:
The orthocenter is the center of the triangle formed by creating all the altitudes of each side.
The altitude of a triangle is formed by creating a line from each vertex that is perpendicular to the opposite side.
In acute traingle , the orthocenter lies inside it.
In right angled triangle, the orthocenter lies on the triangle.
In obtuse triangle , the orthocenter lies outside the triangle because all the three altitudes meet outside .
So, the best explains why the orthocenter of an obtuse triangle is outside the triangle : All three of the altitudes lie entirely outside the triangle.
