® Integration by substitution

® Integration by substitution A change in the variable of integration often reduces an integral to one of the fundamental integrals. The method in which we change the variable to some other variable is called the method of substitution. When the integrand involves some trigonometric functions, we use some well known identities to find the integrals. Using substitution technique, we obtain the following standard integrals. log sec cot log sin (iii) log sec (iv) cosec log cosec cot