Math
posted by Fernando on .
Write each complex number in rectangular form?
I need help with this. :/
2(cos120°+i sin 120°)
and
4(cos 7π/4 + i sin 7π/4)
?

2*cos120 + i2*sin120.
X = hor = 2*cos120 = 1.
Y = VER = 2*sin120 = 1.732.
tanA = Y/X = 1.732/1 = 1.732,
A = 60 deg = 300 deg CCW.
R = X/cosA = = 1/cos300 = 2 = Resultant.
R = 2 @ 60 deg = 2 @ 300 deg CCW.
4*cos7pi/4 + i4*sin7pi/4,
7pi/4 = 7*180/4 = 315 deg.
X = hor = 4*cos315 = 2.83.
Y = ver = 4*sin315 = 2.83.
tanA = Y/X = 2.83/2.83 = 1.
A = 45 deg = 315 deg CCW.
R = X/cosA = 2.83/cos315 = 4.0 = Resultant.
R = 4.0 @ 45 deg = 4.0 @ 315 deg CCW = Resultant.