Download the app

Questions  

The general solution of the equation1sinx+...+1nsinnx+......1+sinx+...+sinnx+......=1cos2x1+cos2xis

a
−1nπ3+nπ,∀n∈I
b
−1nπ6+nπ,∀n∈I
c
−1n+1π6+nπ,∀n∈I
d
−1n−1π3+nπ,∀n∈I

detailed solution

Correct option is B

1−sinx+...+−1nsinnx+......1+sinx+...+sinnx+......=1−cos2x1+cos2x⇒11+sinx.1−sinx1=2sin2x2cos2x⇒2sin2x+sinx−1=0⇒sinx=−1±1+84=−1±34⇒sinx=−1 or sinx=12Since  sinx≠−1 , we have  sinx=12=sinπ6∴x=nπ+−1nπ6

Talk to our academic expert!

+91

Are you a Sri Chaitanya student?


Similar Questions

If 0xπ and 81sin2x+81cos2x=30, then x is equal to


phone icon
whats app icon