how to solve cos^3x csc^3x tan^3x=csc^2x-cot^2x ?

2 Answers
Apr 3, 2018

x=0,pi,2pi,pi/4,5pi/4x=0,π,2π,π4,5π4

Explanation:

cos3xtimes1/(sin3x)timestan3xcos3x×1sin3x×tan3x=1/sin(2x)-cos(2x)/sin(2x)1sin(2x)cos(2x)sin(2x)

1=(1-cos2x)/sin(2x)1=1cos2xsin(2x)

sin(2x)=(1-cos(2x))sin(2x)=(1cos(2x))

2sinxcosx=(cosx)^2+(sinx)^2-(cosx)^2+(sinx)^22sinxcosx=(cosx)2+(sinx)2(cosx)2+(sinx)2

2sinxcosx=2(sinx)^22sinxcosx=2(sinx)2

(sinx)^2-sinxcosx=0(sinx)2sinxcosx=0

sinx(sinx-cosx)=0sinx(sinxcosx)=0

sinx=0sinx=0 or sinx-cosx=0sinxcosx=0

sinx=0sinx=0 or tanx=1tanx=1

x=0,pi,2pi,pi/4,5pi/4x=0,π,2π,π4,5π4


  • I'm giving the answers between 0 and 2pi2π

Apr 3, 2018

Verified below

Explanation:

Using:
cscx=1/sinxcscx=1sinx
cotx= 1/tanxcotx=1tanx
1+cot^2x= csc^2x1+cot2x=csc2x

Start:
cos^3x csc^3x tan^3x=csc^2x-cot^2xcos3xcsc3xtan3x=csc2xcot2x

cos^3x/sin^3x*tan^3x=csc^2x-cot^2xcos3xsin3xtan3x=csc2xcot2x

cot^3 tan^3x=csc^2x-cot^2xcot3tan3x=csc2xcot2x

1/(cancel(tan^3x))* cancel(tan^3x)=csc^2x-cot^2x

1= csc^2x-cot^2x

1+csc^2x-csc^2x= csc^2x-cot^2x

1+csc^2x-(1+cot^2x)= csc^2x-cot^2x

cancel(1)+csc^2xcancel(-1)-cot^2x=csc^2x-cot^2x

Graph of csc^2x-cot^2x
graph{(cscx)^2-(cotx)^2 [-9.96, 10.04, -5.04, 4.96]} = csc^2x-cot^2x#

Graph of cos^3x csc^3x tan^3x
graph{(cosx)^3(cscx)^3(tanx)^3 [-9.96, 10.04, -5.04, 4.96]}