## anonymous 3 years ago What is the modulus of 7 - 8i?

1. anonymous

How do you do this?

2. anonymous

what is modulus?

3. anonymous

hard to explain, at least for me it is

4. mathslover

@mridrik Do you know how to find the modulus of the general form of complex numbers?

5. anonymous

no

6. anonymous

I know like 8 % 12 = 8 and stuff like that

7. mathslover

OK no problem, let me give you an introduction to the modulus of complex numbers.

8. mathslover

Let there be Z (a complex number ) = a + ib So , we have to find the modulus of Z = |Z| = |a+ib| It is given by |Z| = $$\sqrt{x^2+y^2}$$

9. mathslover

oops sorry |Z| = $$\sqrt{a^2+b^2}$$

10. UnkleRhaukus

|dw:1350706728154:dw|

11. anonymous

so positive radical 113?

12. UnkleRhaukus

|dw:1350706781969:dw|

13. mathslover

so let us take the question itself as an example : |7-8i| = $$\sqrt{7^2+8^2}$$= $$\sqrt{49 + 64} = \sqrt{113}$$

14. mathslover

Good work @mridrik , you're right!

15. UnkleRhaukus

right!

16. anonymous

alright thanks, what were you drawing there unkle?

17. UnkleRhaukus

i plotted the point 7 - 8i on an Argand diagram, then used the Pythagorean relation to determine the distance form the origin of the point

18. UnkleRhaukus

from*

19. UnkleRhaukus

modulus is just the length of the vector

20. anonymous

oh, okay