What is the product of 65(cos(14°) + i sin(14°)) and 8(cos(4°) + i sin(4°))?

a) 73(cos(18°) + i sin(18°))
b) 73(cos(56°) + i sin(56°))
c) 520(cos(18°) + i sin(18°))
d) 520(cos(56°) + i sin(56°))

Respuesta :

Answer:

[tex]c)\ 520(\cos(18^\circ)+\mathbf{i}\sin(18^\circ)[/tex]

Step-by-step explanation:

Complex  Numbers in Polar Form

Let Z1 and Z2 two complex numbers in the form:

[tex]Z1 = r_1(\cos\theta_1+\mathbf{i}\sin\theta_1)[/tex]

[tex]Z2 = r_2(\cos\theta_2+\mathbf{i}\sin\theta_2)[/tex]

The product of Z1*Z2 is given by:

[tex]Z1*Z2 = r_1*r_2(\cos(\theta_1+\theta_2)+\mathbf{i}\sin(\theta_1+\theta_2))[/tex]

The given complex number has:

[tex]r_1=65[/tex]

[tex]\theta_1=14^\circ[/tex]

[tex]r_1=8[/tex]

[tex]\theta_1=4^\circ[/tex]

Thus:

[tex]Z1*Z2 = 65*8(\cos(14^\circ+4^\circ)+\mathbf{i}\sin(14^\circ+4^\circ)[/tex]

[tex]\mathbf{Z1*Z2 = 520(\cos(18^\circ)+\mathbf{i}\sin(18^\circ)}[/tex]

Answer:

c

Step-by-step explanation:

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