## mridrik Group Title What is the modulus of 7 - 8i? one year ago one year ago

1. mridrik Group Title

How do you do this?

2. TAKEBACKMATH Group Title

what is modulus?

3. mridrik Group Title

hard to explain, at least for me it is

4. mathslover Group Title

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

5. mridrik Group Title

no

6. mridrik Group Title

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

7. mathslover Group Title

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

8. mathslover Group Title

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 Group Title

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

10. UnkleRhaukus Group Title

|dw:1350706728154:dw|

11. mridrik Group Title

12. UnkleRhaukus Group Title

|dw:1350706781969:dw|

13. mathslover Group Title

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

14. mathslover Group Title

Good work @mridrik , you're right!

15. UnkleRhaukus Group Title

right!

16. mridrik Group Title

alright thanks, what were you drawing there unkle?

17. UnkleRhaukus Group Title

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 Group Title

from*

19. UnkleRhaukus Group Title

modulus is just the length of the vector

20. mridrik Group Title

oh, okay