Multiplying and subtracting coordinates

In summary, the conversation revolves around a problem in a textbook that requires some knowledge of mathematics. The equations S11, S21, S12, and S22 are given and the question of finding |Δ| = |S11 S22 - S12 S21| is raised. After trying different methods, the person eventually figures it out and suggests explaining the solution for others who may encounter a similar problem.
  • #1
OnceMore
23
1
Hello,

I am hoping someone can help me understand a problem in a textbook. It just assumes you know how to do a littel bit of maths, which I don't, and haven't been able to figure out.

S11 = 0.894 [itex]\angle[/itex] -60.6
S21 = 3.122 [itex]\angle[/itex] 123.6
S12 = 0.020 [itex]\angle[/itex] 62.4
S22 = 0.781 [itex]\angle[/itex] -27.6

Then, how does |Δ| = |S11 S22 - S12 S21| = |0.696 [itex]\angle[/itex] -83|

I have tried different things, for example, converting between cartesian and polar etc, but nothing seems to get me there.

Multiplying the respective r parts, and subtracting as needed seemed to get me close there, but doing the same with the angles didn't work out.

Thanks.

-S
 
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  • #2
Oh, sorry ...I just figured it out!

Taking a break and coming back to it does help.

...just a thought, should I explain how it is done in case anyone else is looking to know this sort of thing?

I don't know what the protocol would be on that.

Slán
-S
 

Related to Multiplying and subtracting coordinates

1. What is the difference between multiplying and subtracting coordinates?

Multiplying coordinates involves multiplying the x and y values of a point by a given number, while subtracting coordinates involves subtracting the x and y values of one point from another point.

2. Can you provide an example of multiplying coordinates?

For example, if we have a point (4,6) and we multiply it by 2, the new coordinates would be (8,12). This means that the point has moved 4 units in the x-direction and 6 units in the y-direction.

3. How do you subtract coordinates from each other?

To subtract coordinates, we first subtract the x values and then the y values. For example, if we have two points A(3,5) and B(1,2), the difference between the two points would be (3-1, 5-2) which is equal to (2,3).

4. What is the purpose of multiplying and subtracting coordinates?

Multiplying and subtracting coordinates is useful in various mathematical and scientific applications, such as finding distances between points, scaling geometric figures, and solving equations involving coordinates.

5. Are there any rules or properties to keep in mind when multiplying and subtracting coordinates?

Yes, there are a few rules to keep in mind when performing these operations. For example, multiplying or dividing all coordinates by the same number will result in a scaled version of the original figure. Also, when subtracting coordinates, the order in which the points are subtracted does not affect the final result.

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