First, let
be a point in our parabola. Since we know that the focus of our parabola is the point (0,8), we are going to use the distance formula to find the distance between the two points:
Next, we are going to find the distance between the directrix and the point in our parabola. Remember that the distance between a point (x,y) of a parabola and its directrix,
, is:
. Since our directrix is y=-8, the distance to our point will be:
Now, we are going to equate those two distances, and square them to get rid of the square root and the absolute value:
Finally, we can expand and solve for
:
We can conclude that t<span>he standard form of the equation of the parabola with a focus at (0, 8) and a directrix at y = -8 is </span>
1) The perimeter is the sum of the lengths of the straight edge (the diameter of the semicircle) and the length of the arc of the semicircle.
The circumference of a 4 ft circle is
π*diameter = π*4 ft ≈ 12.566 ft
The semicircle will have a length that is half that, 6.283 ft. When this length is added to the diameter, the perimeter is found to be
Perimeter = 4 ft + 6.283 ft ≈ 10.3 ft.
2) The area of a circle is given by the formula
A = (π/4)d²
For a diameter of 15 inches, the area is
A = (π/4)(15 in)² = 56.25π in²
A ≈ 176.7146 in²
The area of the circle is about 176.71 in².
Answer:
$3.60.
Step-by-step explanation:
4.5 = x + 20% of x
4.5 = x + 0.2x
1.2x = 4.5
x = 3.75
Answer: angle 2 is supplementary to angle 1