Question

Express the complex number in trigonometric form.

-2

Answer 1

hint: -2 = -2 + 0i

Answer 2

2(cos 0° + i sin 0°)?

Answer 3

any number in a+bi form can be converted to trigonometric form

z = r*[ cos(theta) + i*sin(theta) ]

where

r = sqrt(a^2 + b^2)

theta = arctan(b/a)

Answer 4

since -2+0i has a negative component, this means that you'll have to add on 180 degrees to theta (to make sure you're in the right region)

Answer 5

2(cos 0° + i sin 0°) is incorrect

Answer 6

so then it would be 2(cos 180° + i sin 180°)?

Answer 7

to find r, use this formula

r = sqrt(a^2 + b^2)

Answer 8

in this case, a = -2, b = 0

Answer 9

I'm lost now.

Answer 10

-2 = -2+0i

if you were to plot this point on the xy axis (x is the real number line, y is the imaginary number line), then you'd be plotting the point (-2,0)

Answer 11

oh wait, I misread and didn't see you posted 2(cos 180° + i sin 180°)

2(cos 180° + i sin 180°) is correct

Answer 12

thanks