Can Trig Identities Be Proven Using Basic Trigonometric Functions?

Join the discussion
Registration is free. Ask a follow-up in this thread, or start your own.
1 reply · 1K views
ttpp1124
Messages
110
Reaction score
4
Homework Statement
I believed I've proved it right, but can someone confirm?
Relevant Equations
n/a
IMG_4216.jpg
 
Physics news on Phys.org
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.
 
  • Like
Likes   Reactions: berkeman