addition of angles 7 Isaac Physics

hey can anyone help with this question?
https://isaacphysics.org/questions/addition_of_angles7?board=smart24_dm_1_3&stage=a_level

Reply 1

IllegalRazer

Have a quick google on "sum to product"

Reply 2

MrJohnGalt

Original post by IllegalRazer

Have a quick google on "sum to product"

I don't think it's simply sum of product as the answer 2Acos(phi) cos(2pift - ((2pi)/(lambda)) x) is incorrect or am I missing something? I'm assuming some physics is needed so if anyone could help?

(edited 3 months ago)

Reply 3

DFranklin

Original post by MrJohnGalt

I don't think it's simply sum of product as the answer 2Acos(phi) cos(2pift - ((2pi)/(lambda)) x) is incorrect or am I missing something? I'm assuming some physics is needed so if anyone could help?

Your answer is essentially what's expected (though it looks odd as displayed by TSR as it's "eaten" some of your asterisks: note that you need spaces between asterisks if you don't want TSR to think they are intended to be delimiters for text in italics).

So I'm guessing something is just different enough from what it's expecting that it's failing to recognise it. Check that it's rendering of what you've written looks as expected (I had trouble getting it to recognise pi as π at first - not enough white space on my part).