Evaluate the following integrals as a limit of sums:
Formula used:
where,
Let,
Here, f(x) = cos x
Now, by putting x = a in f(x) we get,
f(a) = cos a
f(a + h)
= cos (a + h)
Similarly, f(a + 2h)
= cos (a + 2h)
We know,
Therefore,
{∵ nh = b – a}
{∵ 2 cos A sin B = sin(A + B) – sin(A – B)}