Question

Convert z=6cis (pi) I sent a picture of the question and the multiple choice answerssss

Answer 1

We have the angle in polar form:

`z=6\text{cis}(\pi)`

It's an abreviature of:

`z=6(\cos \pi+i\sin \pi)`

Then, we have to calculate cos(pi) and sin(pi)

We know by the unit circle that:

`\begin{gathered} \cos (\pi)=-1 \\ \sin (\pi)=0 \end{gathered}`

Then we can replace:

`\begin{gathered} z=6(-1+i\cdot0) \\ z=-6 \end{gathered}`

The correct answer is z = -6, which is the first option