Question

Express the complex number in trigonometric form. -4

Answer 1

4(cos 270° + i sin 270°)

4(cos 90° + i sin 90°)

4(cos 0° + i sin 0°)

4(cos 180° + i sin 180°)

Answer 2

\[\Large\rm z=-4+0\mathcal i\]This complex number can be written in the form:\[\Large\rm z=r(\cos \theta+\mathcal i \sin \theta)\]Where,\[\Large\rm r=\sqrt{(-4)^2+0^2}\]and,\[\Large\rm \theta=\arctan\left(\frac{0}{-4}\right)\]We don't need to get that fancy for this problem though.
Simply graphing the point should be enough to see what's going on.