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# Trig problems need help

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1. How can I shows that these two expressions underlined are the same ? thanks
2. (Original post by coconut64)
How can I shows that these two expressions underlined are the same ? thanks
You seem to have some confusion about fractions here...

Step 1) Note

Step 2) What's the definition of ? What about ?

Piece them together.
3. (Original post by Blazy)
You seem to have some confusion about fractions here...

Step 1) Note

Step 2) What's the definition of ? What about ?

Piece them together.
I have managed to work it out from one side but not the other ... thanks
4. cos2y is 1/sec2y, like you said on the left. Just apply that to the RHS as well and you should be sorted - don't just change the cot term
5. Well, you have to recall that
sec2x=1/cos2x and
cot2x=1/tan2x
6. (Original post by bstone13)
cos2y is 1/sec2y, like you said on the left. Just apply that to the RHS as well and you should be sorted - don't just change the cot term
how can I get cos2y at the bottom? I only have cos^2 2y at the top of my fraction and this wouldn't give me sec2y... Thanks
7. (Original post by coconut64)
how can I get cos2y at the bottom? I only have cos^2 2y at the top of my fraction and this wouldn't give me sec2y... Thanks

You have to go back to the beginning. You didn't sub in for cos2y when you should have.

Does it make sense now?

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