Please calculate this limit
please help me​

We want to find:

Here we can use Stirling's approximation, which says that for large values of n, we get:

Because here we are taking the limit when n tends to infinity, we can use this approximation.

Then we get.

Now we can just simplify this, so we get:

And we can rewrite it as:

The important part here is the exponent, as n tends to infinite, the exponent tends to zero.

Thus:

by definition, an arc subtended by a central angle of some given measure has the same measure. so .