Thread: trig identities help needed

so i have my end of prelims coming up and doing a revision test. this question came up


Now i thought that you would do the question like this:



but it gave a different soln. am i wrong?

Originally Posted by link0099

so i have my end of prelims coming up and doing a revision test. this question came up


Now i thought that you would do the question like this:



but it gave a different soln. am i wrong?

Your proof is valid. The book most likely uses which of course if you divide through by gives the identity you used.

oh good, thanks a lot