How to calculate magnitude?

- Use the sets of points below to find the magnitude and components of each vector.
- A(4,-2) and B (3,-2)
- G(-1,7) and H(-4,5)

So if I were to attempt to find the components I'd say

a. = -1, and 0

and

b. = -3. and -2

If I enter it into the magnitude formula I was given I get;

a. = square of{1^{2} + 0^{2})

a. = square of (1)

b.= square of (-3^{2 }+ -2^{2})

b.= square of (13)

In all the sample questions we were given we had numbers with a whole square, or even numbers that were easier to factor, but on the assignment we have these, and no way of confirming that what were doing is correct.

Re: How to calculate magnitude?

Quote:

Originally Posted by

**Urpes** - Use the sets of points below to find the magnitude and components of each vector.
- A(4,-2) and B (3,-2)
- G(-1,7) and H(-4,5)

You mean the vector from A to B and the vector from G to H.

Quote:

So if I were to attempt to find the components I'd say

a. = -1, and 0

and

b. = -3. and -2

Yes, those are correct.

Quote:

If I enter it into the magnitude formula I was given I get;

a. = square of{1^{2} + 0^{2})

a. = square of (1)

b.= square of (-3^{2 }+ -2^{2})

b.= square of (13)

NOT "square of", square **root** of. Very different things! And you do understand that the square root of 1 is 1, right?

In all the sample questions we were given we had numbers with a whole square, or even numbers that were easier to factor, but on the assignment we have these, and no way of confirming that what were doing is correct. [/QUOTE]

Why would having whole number roots give you a way to "confirm" what you were doing?

Re: How to calculate magnitude?

In our practice questions for magnitude not once was there ever a decimal. If it was root of 25 the answer would be 5, if it was root 40 it would be: 2 root 40, but here in b. I have root 13 and I can't factor it so when my answers end up different it just makes me question whether or not I'm doing it correctly.

Re: How to calculate magnitude?

This is an example of what I consider bad teaching technique. There was a news story back when I was in High School (and had to walk there in 10 in deep snow, etc) that many HS graduates had no confidence in their results unless the answer came out to be an integer. When I was teaching I always mixed in "not nice" numbers so the students wouldn't be so shocked to see them in a "real world" setting.

-Dan