- #1

PiRsq

- 112

- 0

If |x|=11 and |y|=23 and |x-y|=30, find |x+y|?

I tried but I couldn't get it, any hints out there guys?

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- Thread starter PiRsq
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- #1

PiRsq

- 112

- 0

If |x|=11 and |y|=23 and |x-y|=30, find |x+y|?

I tried but I couldn't get it, any hints out there guys?

- #2

Hurkyl

Staff Emeritus

Science Advisor

Gold Member

- 14,967

- 19

Try squaring everything.

- #3

PiRsq

- 112

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|x|^2 + |y|^2 = |x+y|^2

Then |x+y|=25.6 units

But my book's answer says 16 units...I dont get it

- #4

Hurkyl

Staff Emeritus

Science Advisor

Gold Member

- 14,967

- 19

Recall that for any vector z:

|z|^2 = z * z

So what should |x + y|^2 and |x - y|^2 be?

- #5

PiRsq

- 112

- 0

Thanks man

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