Rewrite 3+4i in r(cos theta + i sin theta) form.?

Answer 1

r cos t = 3
t sin t = 4
equating real and imaginary part

square and add r = sqrt(3^2+4^2) = 5

devide t = cos^-1(3/5)

so 3+4 i = 5( cos(cos^-(3/5) + i sin(cos^-1(3/5))

Answer 2

r=sqrt(9+16) =5
tan@= 4/3 so cos @=0.6 ans sin @=0.8 so
3+4i= 5(0.6+i*0.8)