Question

How do you write `3i` in trigonometric form?

Answer 1

I found: `z=3i=3[cos(90^@)+isin(90^@)]`

Explanation:

We can find the position of your number on the complex plane:

We have that:
`z=3i=rho[cos(theta)+isin(theta)]` in trigonometric form, where:
`rho=` modulus, the distance from the origin to your point; in this case: `rho=3`
`theta=` angle with the horizontal Real positive semi-axis; in this case: `theta=90^@`.
So you get:
`z=3i=3[cos(90^@)+isin(90^@)]`