C3 trig maths help

Rukia12

I will insert the question and my working out so far:

Reply 1

Rukia12

Ive so far got up to here:

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Reply 2

RDKGames

Study Forum Helper

Original post by Rukia12

Ive so far got up to here:

Should be 2x inside cosine at the end.

Reply 3

Rukia12

Original post by RDKGames

Should be 2x inside cosine at the end.

how to i simplify 2cosxcos pi/3 to cos2x?

Reply 4

RDKGames

Study Forum Helper

Original post by Rukia12

how to i simplify 2cosxcos pi/3 to cos2x?

Again, it should be cos(2x) and not cos(x) in that equation. Apart from that, simply evaluate 2cos(pi/3)

Reply 5

wajeeh1364

You've made a slight mistake in the final step of your working. It should read 2cos(2x)cos(pi/3). cos(pi/3) is 0.5 and you get 2 * 0.5 * cos(2x), which is simply cos(2x).

Reply 6

Rukia12

Original post by RDKGames

Again, it should be cos(2x) and not cos(x) in that equation. Apart from that, simply evaluate 2cos(pi/3)

Oh sorry I didn't understand that earlier !

Reply 7

Rukia12

Original post by wajeeh1364

You've made a slight mistake in the final step of your working. It should read 2cos(2x)cos(pi/3). cos(pi/3) is 0.5 and you get 2 * 0.5 * cos(2x), which is simply cos(2x).