1.

Find the modulus and argument of each of the following complex numbers and hence express each of them in polar form: `((1-i))/(("cos"(pi)/(3)+"i sin"(pi)/(3)))`

Answer» Correct Answer - `sqrt(2),(7pi)/(12),sqrt(2)("cos"(7pi)/(12)-"i sin"(7pi)/(12))`
Given number `=(2(1-i))/((1+sqrt(3)i))xx((1-sqrt(3)i))/((1-sqrt(3)i))={((1-sqrt(3)))/(2)-((1+sqrt(3)))/(2)i}`
`therefore" "|z|^(2)=((1-sqrt(3))^(2))/(4)+((1+sqrt(3))^(2))/(4)=(2(1+3))/(4)=2 rArr |z| = sqrt(2)`.
`tan alpha=|((-(1+sqrt(3)))/(2))/(((1+sqrt(3)))/(2))|=((sqrt(3)+1))/((sqrt(3)-1))=((1+(1)/(sqrt(3))))/((1-(1)/(sqrt(3))))=("tan"(pi)/(4)+"tan"(pi)/(6))/(1-"tan"(pi)/(4)*"tan"(pi)/(6))`
`=tan((pi)/(4)+(pi)/(6))="tan"(5pi)/(12)`.
The given number z is represented by the point `P((-(sqrt(3)-1))/(2),(-(sqrt(3)+1))/(2))`
So, it lies in the third quadrant.
`therefore" "arg(z) = theta = -(pi- alpha)=-(pi-(5pi)/(12))=(-7pi)/(12)`.
Hence, `z=sqrt(2){cos((-7pi)/(12))+i sin((-7pi)/(12))}`.


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