Verify the following 10 1sin2x1cosx cosx 11 1sinx 1cscx c
     Verify the following. 10 1-sin^2x/1-cosx = -cosx  11. 1/sinx - 1/cscx = cosx cotx  12. Sec^4x -tan^4x = 1+2tan^2x 
  
  Solution
10) we have given 1-sin2x/(1-cosx)=-cosx
LHS=1-sin2x/(1-cosx)=(1-cosx-sin2x)/(1-cosx) =(cos2x-cosx)/(1-cosx) =-cosx(1-cosx)/(1-cosx) =-cosx=RHS
the given equation is verified
11) we have given 1/sinx -1/cscx =cosx cotx
LHS=1/sinx -1/cscx =(cscx -sinx)/(sinx cscx) =(1/sinx -sinx)/(sinx cscx)=(1-sin2x)/(sin2x cscx)
=cos2x/(sin2x cscx)=cos2x/(sin2x *1/sinx)=cos2x/(sinx) =cosx*(cosx/sinx)=cosx*cotx =RHS
the given equation is verified
12) we have given sec4x-tan4x=1+2tan2x
LHS=sec4x-tan4x =(sec2x)2-tan4x =(1+tan2x)2-tan4x since sec2x-tan2x=1
=1+tan4x+2tan2x-tan4x
=1+2tan2x = RHS
the given equation is verified

