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.
Answer:
{(0,0),(0,1),(1,2),(1,3)}
Step-by-step explanation:
If this was a function it would be (0,0) ,(1,1), (2,2) ,(3,3) and so on
Answer:
Pt= 7240.7734 ≈ 7241
Step-by-step explanation:
Answer:
3 people attended the banquet
Step-by-step explanation:
The function is given as:
b = 75 + 15n where
b represents the total = 122
n represents the number of people attending = ??
If the total cost of the banquet is 122, how many people attended the banquet?
Hence,
122 = 75 + 15n
122 - 75 = 15n
47 = 15n
Divide both sides by 15
n = 47/15
n = 3.1333333333
Approximately to the nearest whole number = 3
Therefore, 3 people attended the banquet.
Answer:
JL = 31
Step-by-step explanation:
JL is the total length of the line segment. We know that JK is 15 units long and that KL is 16 units long. So, you would add these numbers (15 & 16) together to get the total length of the line segment. Hope this helps! :)
