CameraIcon
CameraIcon
SearchIcon
MyQuestionIcon
MyQuestionIcon
1
You visited us 1 times! Enjoying our articles? Unlock Full Access!
Question

Let α and β be two distinct complex numbers such that |α|=|β|. If real part of α is positive and imaginary part of β is negative, then the complex number (α+β)(αβ) may be

A
zero
No worries! We‘ve got your back. Try BYJU‘S free classes today!
B
real and negative
No worries! We‘ve got your back. Try BYJU‘S free classes today!
C
real and positive
No worries! We‘ve got your back. Try BYJU‘S free classes today!
D
purely imaginary
Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses
Open in App
Solution

The correct option is C purely imaginary
Let Z= α+βαβ
cis(θ)=cosθ+isinθ
Let, |α|=|β|=r&α=rcis(A),β=rcis(B)
Z=cis(A)+cis(B)cis(A)cis(B)
= cosA+cosB+i(sinA+sinB)cosA+cosBi(sinA+sinB)
= cos(AB2)[cos(A+B2)+isin(A+B2)]sin(AB2)[sin(A+B2)icos(A+B2)]
Z=icos(AB2)sin(AB2)
Therefore, Z is purely imaginary.

flag
Suggest Corrections
thumbs-up
0
Join BYJU'S Learning Program
similar_icon
Related Videos
thumbnail
lock
Trigonometric ratios of complementary angles
MATHEMATICS
Watch in App
Join BYJU'S Learning Program
CrossIcon