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diracy
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Homework Statement
(a) Suppose the segment connecting (a,b) to (0,0) has length r[itex]_{1}[/itex] and forms an angle [itex]\theta[/itex][itex]_{1}[/itex] with the positive side of the x-axis. Suppose the segment connecting (c,d) to (0,0) has a length r[itex]_{2}[/itex] and forms an angle [itex]\theta[/itex][itex]_{2}[/itex] with the positive side of the x-axis. Now let (a+bi)(c+di)=x+yi. Show that the length of the segment connecting (x,y) to the origin is r[itex]_{1}[/itex]r[itex]_{2}[/itex] and the angle formed is [itex]\theta[/itex][itex]_{1}[/itex]+[itex]\theta[/itex][itex]_{2}[/itex].
(b) Use the result from (a) to find a complex number z[itex]\in[/itex]C such that z^2=i.
Homework Equations
The Attempt at a Solution
(a+bi)(c+di)=x+yi
ac+adi+bci+bd(i[itex]^{2}[/itex])=x+yi
ac+adi+bci-bd=x+yi
(ac-bd)+(ad+bc)=x+yi
x=(ac-bd), y=(ad+bc)
I'm not sure where to go from here. Just looking for some help. Thanks!