# Is #f(x)=sinx# concave or convex at #x=-1#?

##### 1 Answer

Nov 29, 2016

Since

#### Explanation:

We have to know that

Also recall that concavity and convexity are determined through the sign of the second derivative of a function.

First finding the second derivative:

#f(x)=sinx#

#f'(x)=cosx#

#f''(x)=-sinx#

If

If

We see that

#f''(-1)=-sin(-1)approx08415#

Since