If sin x +sin^2 x=1 then find the value of cos^8 x +2cos^6 x+cos^4 x

(INDEX;^2 : means to the power of)

Asked by keshavendu35 | 17th Aug, 2018, 12:08: AM

Expert Answer:

sinx+sin2x=1
sinx=1sin2x
sinx=cos2x
sin2x=cos4x
so,
cos2x+cos4x=1
Squaring
(cos2x+cos4x)2=12
cos8x+2cos4xcos2x+cos4x=1
cos8x+2cos6x+cos4x=1

Answered by Arun | 17th Aug, 2018, 11:25: AM

Queries asked on Sunday & after 7pm from Monday to Saturday will be answered after 12pm the next working day.