Establish the identity sec - cos = sin x tan

[Timothy]

sec - cos = sin x tan

I thing I have to change sec and tan to sin or cos

Which would be (1/cos) - cos = sin x (sin/cos)

Iam not sure what to do next.

Thanks Tim

 

[tkhunny]

Have you considered adding the fractions on the left?

 

[Timothy]

Do you mean 1/cos + - cos/1

Find common denominator

1/cos + (-cos/1)

1/cos + (-cos^2/cos) = 1-cos^2 I am not sure if I am doing this right.

If I am , I don't know where to go to from here.

Need help.

 

[skeeter]

sec(x) - cos(x) = sin(x)tan(x)

1/cos(x) - cos(x) =

1/cos(x) - cos²(x)/cos(x) =

[1 - cos²(x)]/cos(x) =

now, since sin²(x) + cos²(x) = 1, sin²(x) = 1 - cos²(x) ...

sin²/cos(x) =

sin(x)[sin(x)/cos(x)] = sin(x)tan(x)

 

[Timothy]

Thank you

Thank you

 

[tkhunny]

Re: Do you mean 1/cos + - cos/1

I am not sure if I am doing this right.
I don't know where to go to from here.

Secret: You can't do it "wrong" and no one knows where "to go". Just TRY something. You can't break it. Give it a shot and see what happens. Proceed without fear. If what you are doing seems to be going in the right direction, keep doing it. If you seem to be going nowhere, try something else. No worries.