Grade 12th PassAlgebraONE OR MORE CORRECT If complex no. (1+ri)^3=S(1+i)for some real S then value of r can be A cos pi/5 B cosec 3pi/2 C cot pi/12 D tan pi/12 nitish krishnatra 14 Years agoGrade 12th Pass
Chetan Mandayam NayakarApproved Tutor Answer14 Years agolet (1+ri)^3=x+iy argument of x+iy=3*arctan(3) argument of S(1+i)=(pi/4)+(n*pi), where n is ANY integer 3arctan(r)=pi/4 +n*pi arctan(r)=(pi/12)+(n/3)*pi r=tan((pi/12)+(n*pi/3)), for ANY INTEGER n