jeffstar18
New Member
- Joined
- Mar 20, 2012
- Messages
- 6
- Gender
- Male
- HSC
- 2013
So we did a 45 minute exam where one of the questions asked us to prove that cos4theta = sinsomething + sinsomething + sinsomething (can't remember the coefficients or the powers). You could just do it using double angle expansion, but during the exam I couldn't think of that so I ended up using de moivres theorem, but still got the right answer. The question was phrased as hence or otherwise prove. Can I lose marks?