Question

Show that the equation is not an identity by finding a value of x for which both sides are defines but not equal.

Answer 1

We are given the expression:

`\cos (x-\pi)=\cos (x)`

We, simply replace the values of solution given and then determine in which it is not a solution, but we can see that when we replace x = 0, we will get:

`\cos (\pi)\\e\cos (0)`

So, this proves that the function is not an identity.