Question 996072
Rule:
If 
z1 = r1 * [ cos(theta1)+i*sin(theta1) ]
z2 = r2 * [ cos(theta2)+i*sin(theta2) ]
Then
z1*z2 = (r1*r2) * [ cos(theta1+theta2)+i*sin(theta1+theta2) ]


In plain English:
multiply the r values out front; add the angles


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In this case,


z1 = 8(cos 35° + i sin 35°)
z2 = 8(cos 50° + i sin 50°)


Using the rule above, we get

z1*z2 = (8*8)* [ cos(35°+50°) + i*sin(35°+50°) ]
z1*z2 = <font color="red">64 * [cos(85°) + i*sin(85°)]</font>


So the final answer is <font color="red">64 * [cos(85°) + i*sin(85°)]</font>