the diameter of the sphere is 7 inches. What is the circumference of a cross section through the center of the model?
1 answer:
You might be interested in
Answer:
Part 1) The directrix of the parabola is y=-4.25
Part 2) The focus of the parabola is F(1,-3.75)
Step-by-step explanation:
we have
This is a vertical parabola open upward
we know that
If a parabola has a vertical axis, the standard form of the equation of the parabola is
where
p≠ 0
The vertex of this parabola is at (h, k).
The focus is at (h, k + p).
The directrix is the line y = k - p.
The axis is the line x = h.
step 1
Convert the equation of the parabola in standard form
so
----> equation in standard form
The vertex is the point (1,-4)
4p=1 ------> p=1/4
step 2
Find the directrix of the parabola
The directrix is the line y = k - p
we have
k=-4
p=1/4
substitute the values
y = k - p
y=-4-(1/4)=-17/4
y=-4.25
step 3
Find the focus of the parabola
we know that
The focus is at (h, k + p).
we have
h=1
k=-4
p=1/4
substitute
F(1,-4+1/4)
F(1,-3.75)