Proving trig identities

  • Thread starter ttpp1124
  • Start date
  • #1
110
4
Homework Statement:
I believed I've proved it right, but can someone confirm?
Relevant Equations:
n/a
IMG_4216.jpg
 

Answers and Replies

  • #2
member 587159
I believe it is correct, but note that

$$(\tan^2 x -1)/\sec^2 x = (\tan^2 x -1) \cos^2 x = \sin^2 x - \cos^2 x = - \cos(2x)$$

so you could have been a little faster.
 

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