Question

Can someone explain how to express -4 in trigonometric form? Really lost. Thank you!

Answer 1

Polar form: \(\Large (r,\theta)\)

Trig form: \(\Large r[\cos(\theta) + i*\sin(\theta)]\)

The two forms are very similar

Answer 2

write -4 as -4+0i

that is in the form a+bi

Answer 3

Ok.

Answer 4

a = -4
b = 0

plug those values into the formulas

r = sqrt(a^2 + b^2)
theta = arctan(b/a)

Answer 5

So r = 4 and theta = 0?

Answer 6

r = 4 is correct
but theta = 0 is not

Answer 7

Isn't 0/-4 equal to 0, and the arctan(0) just 0?

Answer 8

arctan(b/a) = arctan(0/(-4)) = 0 is true

but we're in the wrong spot

add on 180 degrees