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LiNnda
Questions (3)
1) ctgx+cosx=1+ctgx*cosx
2) sin^4x+cos^4x=1/2 3) (sinx-cosx)^2=sin2x 4) sin^4x-cos^4x=7/2(sinxcosx) 5)
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8sin^2x+sinxcosx+cos^2x=4
2 answers
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2cos^2x-3sinx=0
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Answers (3)
2) sin^4x+cos^4x=1/2 sin^2x*sin^2x+cos^4x=1/2 (1-cos^2x)(1-cos^2x)+cos^4x=1/2 1-cos^2x-cos^2x+2cos^4x=1/2 2cos^4x-2cos^2x+1=1/2 2cos^4x-2cos^2x+1/2=0 x=pi/4+2kpi x2=7pi/4+2kpi
thank u very much!
tan^2x(1+cot^x)=1/(1-sin^2x) tan^2x(1+1/tan^2x)=1/cos^2x tan^2x+(tan^x/tan^2x)=1/cos^2x tan^2x+1=1/cos^2x sin^2x/cos^2x+1=1/cos^2x (sin^x+cos^2)/cos^2x=1/cos^2x 1/cos^2x=1/cos^2x
