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Trigonometry watch

1. How does sin^2(2x)= (1-cos(4x))/2 ? I just can't work it out!

Thanks!
2. (Original post by rpnom)
How does sin^2(2x)= (1-cos(4x))/2 ? I just can't work it out!

Thanks!
Re-arrange the double angle formulae for to get:

, agree?

Then set .

Also, moved to maths.
3. (Original post by Zacken)
Re-arrange the double angle formulae for to get:

, agree?

Then set .

Also, moved to maths.
Thank you so much! It seems so simple now! I was trying to figure it out for ages!
4. (Original post by rpnom)
Thank you so much! It seems so simple now! I was trying to figure it out for ages!
No problem, it comes in useful all the time when integrating squared trigonometric functions. Remember that also:

5. I am 1 hour too late

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