Use the difference identity to rewrite cos(x-pi/4) .The answer is sqrt2/2(cosx+sinx) but how do you get the answer using the difference identity?
2007-06-11 16:42:21 · 3 answers · asked by Anonymous in Science & Mathematics ➔ Mathematics
cos (x - π/4)
= cos x cos π/4 + sin x sin π/4 (difference identity)
= cos x (√2 / 2) + sin x (√2 / 2)
= (√2 / 2) (cos x + sin x)
2007-06-11 16:46:15 · answer #1 · answered by Scarlet Manuka 7 · 0⤊ 0⤋
cos (a-b)=cos a cos b+sin a sin b so
cos (x-Ï/4)=cos x cos Ï/4 + sin x sin Ï/4
cos (x-Ï/4)=â2 /2 *cos x +â2 /2 *sin x
cos (x-Ï/4)=(â2 /2)(sin x +cos x)
2007-06-12 00:00:34 · answer #2 · answered by yupchagee 7 · 0⤊ 0⤋
cos (x - Ï/4)
= cos x.cos(Ï/4) + sin x.sin(Ï/4)
= (1/â2).cos x + (1/â2).sin x
=(1/â2).(cos x + sin x)
= (â2 / 2).(cos x + sin x)
2007-06-12 06:36:55 · answer #3 · answered by Como 7 · 0⤊ 0⤋