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

If the function f(x)=cos2x+cos2(π3+x)cos x cos(π3+x) is constant (independent of x), then the value of this constant is

A
34
Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses
B
1
No worries! We‘ve got your back. Try BYJU‘S free classes today!
C
43
No worries! We‘ve got your back. Try BYJU‘S free classes today!
Open in App
Solution

The correct option is A 34
f(x)=12(1+cos 2x)+12(1+cos(2π3+2x))2 cos x cos(π3+x)2
=1+12[cos 2x+cos(2π3+2x)cos(2x+π3)cos(π3)]
=34+12[cos 2x+cos(2x+2π3)cos(2x+π3)]
=34+12[cos2x2sin(2x+π2)sin(π6)]
=34+12[cos 2x2 sin(π2+2x).12]
=34+12[cos 2xcos 2x]=34

flag
Suggest Corrections
thumbs-up
3
Join BYJU'S Learning Program
similar_icon
Related Videos
thumbnail
lock
Standard Expansions and Standard Limits
MATHEMATICS
Watch in App
Join BYJU'S Learning Program
CrossIcon