Search results

So I'm pretty sure I've just bought a shit textbook, but can anyone explain the following questions (unless they are, as suspected, incorrect)? Thanks - I'd really appreciate it.

yeah, it was prove, Sanjeet. thanks heaps kkmok. But Sanjeet, you're right, never heard of that identity cos x cos y = 1/2 [cos(x+y) + cos(x-y)]

Hey, Can anyone help me out on this question? Its 13k in Exercise 2A of the Year 12 3U Cambridge Book. The question is as follows cos2A.cos2B-sin2A.sin2B=(cos2A+cos2B)/2 Can't get it! :confused2: Cheers