Question #431bc
2 Answers
Feb 12, 2018
Explanation:
I can't prove it.
Feb 12, 2018
See explanation
Explanation:
There are multiple ways to show this
A common way is to use the definition of a derivative,
which is nicely done here on the site
Another way is to use series expansions
Cosine and sine can expressed as the series expansions

#cos(x)=1/(0!)x^2/(2!)+x^4/(4!)x^6/(6!)...# 
#sin(x)=x/(1!)x^3/(3!)+x^5/(5!)x^7/(7!)...#
Take the derivative of cosine