Stumped on Proving an Identity: Need Help!

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In summary, the conversation is about trying to prove the identity sin2x/1-cos2x = cotx, and the speaker is having trouble with it. They ask for a hint and are reminded to write the formula correctly. The identity can be derived using double angle formulas.
  • #1
Ax
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Ive been trying to prove this identity for the past hour, and I can't seem to do it. I am starting to think its not possible. Heres the identity.
sin2x/1-cos2x = cotx
Can anyone give me some kind of hint. :frown:
 
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  • #2
First of all, learn to write your formulas PROPERLY! :grumpy:
There is a vast difference between sin(2x)/1-cos(2x) and sin(2x)/(1-cos(2x)).
The last one is the expression you should have used.

To derive the identity, recall the double angle formulas.
 
  • #3
Substitute the formula 2cos^x - 1 for cos2x and 2sinxcosx for sin2x. then you just straight away ge the answer.
 

1. What is an identity in mathematics?

An identity in mathematics is an equation that is true for all values of the variables involved. It is a statement that is always true, regardless of the specific values of the variables.

2. How do I know if an equation is an identity?

To determine if an equation is an identity, you can try substituting different values for the variables and see if the equation holds true for all of them. Another way is to simplify both sides of the equation and see if they are equal to each other.

3. What are some common identities in mathematics?

Some common identities in mathematics include the Pythagorean identity, which relates the sides of a right triangle, and the double angle identities, which are used to express trigonometric functions in terms of other trigonometric functions.

4. How can I prove an identity?

To prove an identity, you need to manipulate one side of the equation using algebraic properties and rules until it is equivalent to the other side. This shows that both sides are equal and therefore the equation is an identity.

5. What should I do if I am stumped on proving an identity?

If you are having trouble proving an identity, try looking for patterns or relationships between the different terms in the equation. You can also try working backwards from the desired outcome or using known identities to manipulate the equation. It can also be helpful to take a break and come back to the problem with a fresh perspective.

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