## anonymous one year ago Express the complex number in trigonometric form. -6i

1. anonymous

2. hartnn

to convert it to trigonometric form, you need to find r and $$\theta$$ bring 6i in the form of x+iy then $$r = \sqrt{x^2+y^2}$$ and $$\theta = \arctan(y/x)$$

3. hartnn

then your trigonometric form will be $$r (\cos \theta + i \sin \theta)$$

4. hartnn

** -6i

5. anonymous

6(cos 90 + i sin 90)?

6. hartnn

sure?

7. hartnn

lets verify 6 cos 90 = 6*0 = 0 6 sin 90 = 6 so its actually +6i but we need -6i

8. anonymous

oh!!! 6(cos 180 + i sin 180)

9. hartnn

not actually... cos 180 is not 0.. we just need a negative sign in between, so we can take the angle as -90 and whats the positive angle representation of -90 ??? hint: add 360

10. anonymous

270...

11. hartnn

yep