1. `A=5+6i`
Find roots(4,A)Solution:Here `A=5+6i`
For a complex number `z=a+bi`, the polar form is `z=r*(cos(theta)+i*sin(theta))`
then all `n^(th)` roots of given complex number can be obtained by the De Moivre's Formula i.e.
`w_k=[r*(cos(theta)+i*sin(theta))]^(1/n)=root (n)(r)*[cos((theta+2kpi)/n)+i*sin((theta+2kpi)/n)]`, where `k=0,1,2..,n-1`
Here `n=4`
Step-1: Convert to polar form: `z=r*(cos(theta)+i*sin(theta))`Here, `a=5` and `b=6`
`:. r=sqrt(5^2+6^2)=sqrt(25+36)=sqrt(61)=7.8102`
`theta=atan(b/a)` (Since `a>0`)
`:. theta=atan((6)/(5))`
`:. theta=atan(1.2)`
`:. theta=50.1944 ^circ` or `theta=0.8761` rad
`:. theta=0.8761`
The polar form is `r*(cos(theta)+i*sin(theta))`
`=7.8102*(cos(0.8761)+i*sin(0.8761))`
Step-2: All `n^(th)` roots of given complex number `r*(cos(theta)+i*sin(theta))` is
`w_k=root (n)(r)*[cos((theta+2kpi)/n)+i*sin((theta+2kpi)/n)]`, `k=0,..,n-1`Hence the 4 roots are
for `k=0``w_0=1.6717*[cos((0.8761+2*0*pi)/4)+i*sin((0.8761+2*0*pi)/4)]`
`w_0=1.6717*[cos(0.219)+i*sin(0.219)]`
`w_0=1.6318+0.3632i`
for `k=1``w_1=1.6717*[cos((0.8761+2*1*pi)/4)+i*sin((0.8761+2*1*pi)/4)]`
`w_1=1.6717*[cos(1.7898)+i*sin(1.7898)]`
`w_1=-0.3632+1.6318i`
for `k=2``w_2=1.6717*[cos((0.8761+2*2*pi)/4)+i*sin((0.8761+2*2*pi)/4)]`
`w_2=1.6717*[cos(3.3606)+i*sin(3.3606)]`
`w_2=-1.6318-0.3632i`
for `k=3``w_3=1.6717*[cos((0.8761+2*3*pi)/4)+i*sin((0.8761+2*3*pi)/4)]`
`w_3=1.6717*[cos(4.9314)+i*sin(4.9314)]`
`w_3=0.3632-1.6318i`