expresss complex number in rectangular form
$$\sqrt{7}*cis*2.1 $$

Question

expresss complex number in rectangular form 
$$\sqrt{7}*cis*2.1 $$

anonymous · Answer

is that cosine ?

anonymous · Answer

its cis cos+isin

anonymous · Answer

yes it is stupid notation for $$cos(\theta)+i sin(\theta)$$

anonymous · Answer

im trying square of 7 which is 2.64 times cos but cos(?)

anonymous · Answer

i also assume that you are working in radians, not degrees.  So just use a calculator.
$$\sqrt{7} [cos(2.1)+i sin(2.1)]$$

anonymous · Answer

i get -1.336 for a and 2.284 for b (rounded) so answer is -1.336 + 2.284 i

amistre64 · Answer

the cosine part relates to the x coord; the i sin part relates to the y coord right?

amistre64 · Answer

Did the others parse it tight to be:

cos(2.1) + i sin(2.1)?

amistre64 · Answer

(-1.34, 42.30) is what i get with radian measurements...

amistre64 · Answer

2.28.. musta hit a wrong buttononthe calc :)

anonymous · Answer

yes cosine is x and sine is y, usually written as a and b as in a + bi.  
I doubt it is (-1.34,42.3) for two reasons:
the rectangular form of a complex number is a number, not a coordinate.
so it should look like a + bi
also we know that the absolute value of that number is $$\sqrt7$$

amistre64 · Answer

correct, its similar to polar coordinates in that respect.

But i think the exercise here is to see that complex numbers are nothing new and that they can be plotted in the same manner as rectangular coords...right?