Question

Simplify the expression sin(x+pi)/cos(x-pi)

Answer 1

Use these identities:\[\sin(a\pm b)=\sin a\cos b\pm \sin b\cos a\\
\cos(a\pm b)=\cos a\cos b\mp \sin a\sin b\]

Answer 2

Thank you, but I still don't get it. Could you show me what the first step would be?

Answer 3

\[\frac{\sin(x+\pi)}{\cos(x-\pi)}=\frac{\sin x\cos \pi+\sin \pi\cos x}{\cos x\cos \pi+\sin x\sin \pi}\]
What are the values of \(\sin \pi\) and \(\cos \pi\)?

Answer 4

0 and -1, so would the answer be cotx?

Answer 5

Close, you have a sine in the numerator and cosine in the denominator.

Answer 6

Oh woops, so tanx?

Answer 7

Yes

Answer 8

Thank you so much! (:

Answer 9

yw!