How do you express the complex number in rectangular form: z=5(cos 120degrees + i sin 120 degrees)z=5(cos120degrees+isin120degrees)?

1 Answer
Feb 18, 2016

(-5/2 , 5/2sqrt3 )(52,523)

Explanation:

using the formulae that links Polar to Rectangular coordinates.

• x = rcostheta x=rcosθ

• y = rsintheta y=rsinθ

here r = 5 and theta = 120^@ θ=120

hence : x = 5cos120^@ = 5 xx -1/2 = -5/2 x=5cos120=5×12=52

and y = 5sin120^@ = 5 xxsqrt3/2 = 5/2 sqrt3 y=5sin120=5×32=523