Originally Posted by

**sberxa** Hi

I'm studying for my midterm and am really confused.

One ofthe practice questions is that I am supposed to show that

lsinx-sinyl 'is less than or equal to' lx-yl

using the Mean Value Theorum.

I thought the mean value theorum is pretty much this.

so lsinx-sinyl/lx-yl is less than or equal to zero

meaning the derivative of f(t)=sint is less than zero

so cos(t) is less that zero. Okay, so cos(t)=lsinx-sinyl/lx-yl

and now I'm stuck. How do I prove this statement. Isn't it a proof of itself?

Also, do the absolute value signs matter or can I basically just ignore them.

Thanks!