<p>Hi guys! This is my first CC post (how exciting). Anyway, I know this question is beyond stupid, but what is the derivative of -sinx? At first, I thought it was -cosx but now I'm all confused.</p>
<p>It is -cos x.</p>
<p>Just remember these rules:
d/dx sin x = cos x
d/dx cos x = -sin x</p>
<p>it is -cosx</p>
<p>third that, but whats confusing you about it? just look at their graphs if you are ever not sure whichone's which</p>
<p>thanks guys!! lynda, i dont really know what was confusing me. I just could not process how it was true when d/dx cos x = -sin x, but now I get it.</p>
<p>If you're not sure, just use your rules...</p>
<p>-sin x=(-1)(sin x)</p>
<p>Using the product rule, you get 0+(-1)(cos x)=-cos x.</p>