answer this please

Question

answer this please

anonymous · Answer

this

anonymous · Answer

yes that

anonymous · Answer

$$-4 -4\sqrt{3}i $$

anonymous · Answer

did you try it on the calculator?

anonymous · Answer

-4-6.9 i

anonymous · Answer

thats as simplified as it gets :)

anonymous · Answer

express it in trigonometric form :((

anonymous · Answer

youve gotta answer somethin first lol @ilikephysics2

hartnn · Answer

x+iy = r cos theta + i r.sin theta.

anonymous · Answer

i can't relate with you because we haven't taken that during our discussion :((

hartnn · Answer

so u have x and y 
r= $\sqrt{x^2+y^2}$
$\huge\theta=tan^{-1}\frac{y}{x}$

anonymous · Answer

how is that?

anonymous · Answer

8cis240degrees

hartnn · Answer

do u know how to find magnitude of complex numbers ?

anonymous · Answer

no:((

anonymous · Answer

can you explain it ? :)

hartnn · Answer

magnitude of x+iy is $\sqrt{x^2+y^2}$
and magnitude of r cos theta + i r.sin theta is r.

anonymous · Answer

i found the value of r which is 8 and what will i do next??

anonymous · Answer

theta is 60 , what to do next?

hartnn · Answer

u write it in the form of r (cos theta + i sin theta).

anonymous · Answer

how will i arrive in the answer 8cis240degrees??

hartnn · Answer

u have the answer ?

anonymous · Answer

yes.. but i don't know how will i arrive in that answer..

hartnn · Answer

8cis240degrees is certainly not the answer......

hartnn · Answer

what actual answer u have ?

anonymous · Answer

that is what the higher year gave to me, but he didn't show me how to solve it and that's why im asking this..
the possible answers are:
a. 8cis120  b. 8cis240  c. 8cis150  d. 8cis300

hartnn · Answer

so the question was to find REAL PART of that ??

hartnn · Answer

and thhat is COS not CIS

anonymous · Answer

the question is this: express -4-4(square root of)3 i in trigonometric form..
i guess the letter "i" means it is imaginary and that is why it is written CIS?? but i just guess that..

hartnn · Answer

u got 8, right?...now u calculated theta as tan inverse of root 3, right ?
u got 60.
but, tan inverse of root 3 is also 240
so 8cos240

hartnn · Answer

may be its the short of 8(cos 240 + i sin 240)

anonymous · Answer

i don't know :)) but thank you for the answer :))

hartnn · Answer

remember those conversion formulas.........

anonymous · Answer

yes i will :))