Alternative means By comparing the first four terms, show that the Maclaurin series for cos2x can be found (a) by squaring the Maclaurin series for cos x or (b) by using the identity cos2x = (1 + cos2x)/2.

Solution 68EStep 1:We have to find the Maclaurin series for by(a) by squaring the Maclaurin series for cos xor(b) by using the identity Step 2:We cannot use the statement (a) here,but we can find it by (b).We all know that The first 4 terms of the Maclaurin series for