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/4#

Explanation:

#cos3xtimes1/(sin3x)timestan3x#=#1/sin(2x)-cos(2x)/sin(2x)#

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

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

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

#2sinxcosx=2(sinx)^2#

#(sinx)^2-sinxcosx=0#

#sinx(sinx-cosx)=0#

#sinx=0# or #sinx-cosx=0#

#sinx=0# or #tanx=1#

#x=0,pi,2pi,pi/4,5pi/4#


  • I'm giving the answers between 0 and #2pi#

Apr 3, 2018

Verified below

Explanation:

Using:
#cscx=1/sinx#
#cotx= 1/tanx#
#1+cot^2x= csc^2x#

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

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

#cot^3 tan^3x=csc^2x-cot^2x#

#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]}