Question #8331a

1 Answer
Mar 20, 2016

As below

Explanation:

To Prove (tanx+cotx)^4=csc^4 x cdot sec^4 x(tanx+cotx)4=csc4xsec4x
LHS =(tanx+cotx)^4=(tanx+cotx)4
write tanx and cot xtanxandcotx in terms of sin and cossinandcos
LHS =(sinx/cosx+cosx/sinx)^4=(sinxcosx+cosxsinx)4, simplify
=> ((sinx xxsinx+cosx xxcosx)/(cosx cdot sinx))^4(sinx×sinx+cosx×cosxcosxsinx)4
=> ((sin^2x +cos^2x)/(cosx cdot sinx))^4(sin2x+cos2xcosxsinx)4, Use Identity sin^2x +cos^2x=1sin2x+cos2x=1
=> (1/(cosx cdot sinx))^4(1cosxsinx)4 by definition of sec and cscsecandcsc
=> (sec x cdotcscx)^4(secxcscx)4
=> sec^4 x cdotcsc^4x =sec4xcsc4x=RHS