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)}







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