- #1

- 110

- 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?

You are using an out of date browser. It may not display this or other websites correctly.

You should upgrade or use an alternative browser.

You should upgrade or use an alternative browser.

- Thread starter PiRsq
- Start date

- #1

- 110

- 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

- 14,916

- 19

Try squaring everything.

- #3

- 110

- 0

|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

- 14,916

- 19

Recall that for any vector z:

|z|^2 = z * z

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

- #5

- 110

- 0

Thanks man

Share: