Direct Proportion and The Straight Line Graph
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Straight line graphs that go through the origin, like the one immediately below, show that the quantities on the graph are in direct proportion. This graph states, therefore, that A is directly proportional to B. It also states that B is directly proportional to A, but we are going to work with the statement 'A is directly proportional to B'.
For the above graph:
This is how you write a direct proportion. The symbol in the middle is the Greek letter alpha.
It reads: A is directly proportional to B.
It means: By whatever factor A changes, B changes by the same factor.
So, let's look at the graph and see if by whatever factor A changes, B changes by the same factor.
This is what we are looking for, as we go from 'sub 1' to 'sub 2':
About the factor changes:
Below is an example of a point on this graph. The point is (B1, A1) and it has coordinates (1, 1).
For the above graph:
Coordinate for B1.
Coordinate for A1.
We will check for this shape of a graph if we change A by some factor, does B truly change by the same factor, thus showing that this straight line through the origin represents a direct proportion. In the graph below we change the quantity A by a factor of 3; that is, we triple it.
For the above graph:
Coordinates for (B1, A1).
Coordinates for (B2, A2).
Going from 'sub 1' to 'sub 2', A changes by a factor of 3. That is, A1 times a factor of 3 equals A2.
Going from 'sub 1' to 'sub 2', B also changes by a factor of 3. Likewise, B1 times a factor of 3 equals B2.
Both A and B change by the same factor. That factor is 3.
Therefore, A is directly proportional to B.
Again, the picture:
Let's try this below again for another point using the same graph. Here's the picture:
These steps show the factor changes:
For the above graph:
Coordinates for (B1, A1).
Coordinates for (B2, A2).
Going from 'sub 1' to 'sub 2', A changes by a factor of 4.
Going from 'sub 1' to 'sub 2', B also changes by a factor of 4.
Both A and B change by the same factor. That factor is 4.
Therefore, A is directly proportional to B.
Again:
This straight line graph really tells two stories. If you can say that A is directly proportional to B, then you can state that B is directly proportional to A. The above works out the same.
The function in the graph used here is:
Or, using formal function definition writing:
Lastly:
If someone says, 'A is proportional to B', they most assuredly mean, 'A is directly proportional to B'. Some might feel that the constant inclusion of the word 'direct' is unnecessary. It does, though, get to exactly what you are talking about, because there are other types of proportions
Answer:
The answer to your question is A = 441.50 km²
Step-by-step explanation:
Data
Big triangle Small triangle
base = 33 km base = 19 km
height = 40 km height = 23 km
Process
1.- Calculate the area of the big triangle
Area = base x height / 2
Substitution
Area = 33 x 40 / 2
= 1320 / 2
= 660 km²
2.- Calculate the area of the small triangle
Area = 19 x 23 / 2
= 437 / 2
= 218.5 km²
3.- Subtract the small area to the big area
Share area = 660 - 218.5
= 441.50 km²
See the attached diagram, it has all the information you need.
(a) If the green radii are all 1, then the orange diameters are all 2 + √2, so that the orange radii are (2 + √2)/2 = 1 + √2/2.
This is because we can join the radii of two adjacent green circles to form the sides of a square with side length equal to twice the radius - i.e. the diameter - of the green circles. The diagonal of any square occurs in a ratio to the side length of √2 to 1. Then we get the diameter of an orange circle by summing this diagonal length and two green radii, and hence the radius by dividing this by 2.
(b) We get the blue diameter in the same way. It has length (2 + √2) (1 + √2/2) = 3 + 2√2, so that the blue radius is (3 + 2√2)/2 = 3/2 + √2.
Y= 7x +49
hope this helps x
Answer:
i really dont know what you are saying, but thanks for the points and have a nice day! always smile peeps!
