## anonymous 3 years ago Plotting complex numbers?

1. anonymous

Ive got , $-5\sqrt{3} -$

2. anonymous

Plot them on an argand diagram, where the Y axis is in terms of i

3. anonymous

I meant $-5 \sqrt{3} -5i$ How do I plot the sqrt 3?

4. anonymous

One sec, I got to look something up

5. anonymous

so, -5(root)3 would be your x coordinate then -5i would be your y

6. anonymous

I guess you just have to work out roughly where -5(root)3 would be on your x axis

7. anonymous

it's going to be at about -8.5

8. anonymous

Alright, & -5i means its gonna be on the y axis right?

9. anonymous

Yeah, -5i is on the y axis, however, the Y acis on an argand diagram is actually in terms of i

10. anonymous

You can use the fact that there is a 30-60-90 triangle involved. This means you can find the point exactly. Sound a bit complicated, so I'll try to make a drawing... (just hold on a sec!)

11. anonymous

30-60-90 triangle? O_O

12. anonymous

Here is what I mean: (It is drawn as point D)

13. anonymous

The circle has a radius 10.

14. anonymous

Ah Ok, I get it.!

15. anonymous

You can recognise it by the combination of numbers, e.g. 2+2√3 i, or 5√3-5i...

16. anonymous

Got it

17. anonymous

Nice!

18. anonymous

(Don't mean to be rude, but this image could also help - even if you already understand ;) )

19. anonymous

How would I plot 2 + i ? Would it make the 2 on the y axis also?

20. anonymous

2 to the right, 1 up: a+bi corresponds to point (a, b)...

21. anonymous

Alrighty, thank you.!