wiz-icon
MyQuestionIcon
MyQuestionIcon
1
You visited us 1 times! Enjoying our articles? Unlock Full Access!
Question

If z22zcosθ+1=0 , then z2+z2 is equal to

A
2cos2θ
Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses
B
2sin2θ
No worries! We‘ve got your back. Try BYJU‘S free classes today!
C
2cosθ
No worries! We‘ve got your back. Try BYJU‘S free classes today!
D
2sinθ
No worries! We‘ve got your back. Try BYJU‘S free classes today!
Open in App
Solution

The correct option is B 2cos2θ
We have, z22zcosθ+1=0
z=2cosθ±4cos2θ42=cosθ±cos2θ1
=cosθ±sin2θ=cosθ±i2sin2θ=cosθ±isinθ
when z=cosθ+isinθ
z2+z2=cos2θ+isin2θ+(cos2θisin2θ)=2cos2θ
and when z=cosθisinθ
z2+z2=cos2θisin2θ+(cos2θ+isin2θ)=2cos2θ

flag
Suggest Corrections
thumbs-up
0
Join BYJU'S Learning Program
similar_icon
Related Videos
thumbnail
lock
Multiple and Sub Multiple Angles
MATHEMATICS
Watch in App
Join BYJU'S Learning Program
CrossIcon