OK, so the graph is a parabola, with points x=0,y=0; x=6,y=-9; and x=12,y=0
Because the roots of the equation are 0 and 12, we know the formula is therefore of the form
y = ax(x - 12), for some a
So put in x = 6
-9 = 6a(-6)
9 = 36a
a = 1/4
So the parabola has a curve y = x(x-12) / 4, which can also be written y = 0.25x² - 3x
The gradient of this is dy/dx = 0.5x - 3
The key property of a parabolic dish is that it focuses radio waves travelling parallel to the y axis to a single point. So we should arrive at the same focal point no matter what point we chose to look at. So we can pick any point we like - e.g. the point x = 4, y = -8
Gradient of the parabolic mirror at x = 4 is -1
So the gradient of the normal to the mirror at x = 4 is therefore 1.
Radio waves initially travelling vertically downwards are reflected about the normal - which has a gradient of 1, so they're reflected so that they are travelling horizontally. So they arrive parallel to the y axis, and leave parallel to the x axis.
So the focal point is at y = -8, i.e. 1 metre above the back of the dish.
For this case, as Josh worked more than 40 hours, he was able to receive a payment
($ 8.20 / h) * (40 h) = 328
1.5(8.20) *8.75 = <span>
<span>107.625
</span></span> 328+107.625= 435.625
the gross earnings for Pruitt are 435.625 $
Answer:
$28.50
Step-by-step explanation:
multiply 30 by 5 then divide by 100 and subtract the answer by 30
30×5=150
150÷100=1.5
30-1.5=28.50
Answer:
Bob at the store
Step-by-step explanation:
Bob is at a store and wants to buy a banana, last time he checked it costed 2/6 of a dollar. Now it costs 3/4 times more.
Answer:
54,706 > 45,802
Step-by-step explanation:
Well, as you know, the > symbol means that one number has a greater value than another. For example, 2 > 1. The way we can find that out is using subtraction. Take 54,706 - 45,802, and if that number is positive, then the first number is greater than the other.
54,706 - 45,802 = 8,904
8,904 is a positive.
Therefore, 54,706 > 45,802.
