#Complex numbers in their polar form

26 messages · Page 1 of 1 (latest)

orchid zephyr
#

I am supposed to write (1+i)^(1/2) to its polar form. However, I fail to get the right result. I always get a wrong angle. I don't know how to proceed.

high caveBOT
orchid zephyr
#

This is how I calculated the length:

pseudo shadowBOT
#

Fischstaebchen
Compile Error! Click the errors reaction for more information.
(You may edit your message to recompile.)

orchid zephyr
#

Normally I'd calculate the angle using $arctan\left(\frac{y}{x}\right)$ but that doesn't lead to the expected result $\frac{\pi}{8}$ or 22.5°

pseudo shadowBOT
#

Fischstaebchen

orchid zephyr
#

If you reply please ping me otherwise I might not see it.

orchid zephyr
#

<@&286206848099549185>

steady cedar
orchid zephyr
#

whoops sorry I meant arctan

steady cedar
#

Can u show ....whatever u have worked out ?

orchid zephyr
#

I tried it this way:

pseudo shadowBOT
#

Fischstaebchen

orchid zephyr
#

but I didn't get the right result with that

#

I got 32.7651° instead of the expected 25.5°

quiet copper
#

Can't you just find the angle of 1+i and half the result ?

#

That's certainly easier

#

And 22.5° shows up easily this way

orchid zephyr
#

yeah but why can I simply half it ?

quiet copper
#

arg(z^2) = 2 arg(z), cause arg works nicely with products of complex numbers

#

But yeah you'd have to be wary which square root you take tbh

#

Cause the two square roots of 1+i certainly don't have the same argument

solemn cargo
#

I would go directly to polar first, then compute the root $$1+i= \sqrt{2}e^{i \frac{\pi}{4}}$$
$$(1+i)^{1/2} = \sqrt[4]{2}e^{i \frac{\pi}{8}}$$

pseudo shadowBOT
#

Merosity

orchid zephyr
#

that's definitely easier yeah I will go with that, thank you. I think the root confused me for no reason

#

.solved