Answer:
60 1/2
Step-by-step explanation:
Answer:
Step-by-step explanation:
Applying Pythagoras theorem on right angle triangle
Diameter=2 x radius
The equation that describes the which gives the area of the pen, A, as a function of x, the length of fence parallel to the barn is A = 130x - x²
<h3>How to find area of a rectangle?</h3>
The pen is rectangular. Therefore,
area of a rectangle = lw
where
Therefore,
perimeter = 2w + l
perimeter = 2w + x
130 = 2w + x
130 - x = 2w
w = 65 - 1/ 2 x
A = xw
A = x(65 - 1/ 2 x)
A = 65x - 1 / 2 x²
Therefore, the function that represents A, the area of the pen is as follows:
A = 130x - x²
learn more on rectangle here: brainly.com/question/12685460
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Answer:
3 hours
Step-by-step explanation:
3 Men-5 hours
5 men-?
1 man-3×5= 15 hours
therefore 5 men =15÷5= 3 hours
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.
