select the correct answer.
which of the following is not an identity for ?

cosx(1-sinx) and ±√(1-cosx)/(1+cosx

Step-by-step explanation:

Given

let x/2 =a then

1-cosx/sinx will be

1-cos2a/sin2a

using cos2x=1-2sin^2x

using sin2x= 2cosxsinx

1-1+2sin^2a/2cosasina

2sina/2cosa

sina/cosa

tana

a=x/2

tana=tanx/2

if x/2=a thensinx/(1+cosx) will be

sin2a/1+cos2a

using sin2x=2cosxsinx and cos2x=-1+2cos^2x

2cosasina/1-1+2cos^2a

2sina/2cosa

sina/cosa

tana

as a=x/2

tana=tanx/2

1-cosx/sinx , sinx/(1+cosx) are identities of tan(x/2)

Both cosx(1-sinx) and ±√(1-cosx)/(1+cosx) are not identities of tan(x/2)!  

-13

step-by-step explanation:

f(x)=2x-5 for f(-4)

f(-4)   means let x=-4

f(-4) = 2(-4) -5

f(-4) =-8-5

      = -13

7

step-by-step explanation:

the answer would be 7