{"id":4066,"date":"2021-08-15T18:25:42","date_gmt":"2021-08-15T18:25:42","guid":{"rendered":"https:\/\/mathemerize.com\/?p=4066"},"modified":"2021-11-26T01:29:17","modified_gmt":"2021-11-25T19:59:17","slug":"integration-of-trigonometric-function","status":"publish","type":"post","link":"https:\/\/mathemerize.com\/integration-of-trigonometric-function\/","title":{"rendered":"Integration of Trigonometric Function"},"content":{"rendered":"
Here you will learn integration of trigonometric function with examples.<\/p>\n
Let’s begin –<\/p>\n
\n(i)<\/strong>\u00a0 \\(\\int\\) \\(sin^mxcos^nx\\)<\/p>\n
Case-1<\/strong> : When both m & n \\(\\in\\) natural numbers.<\/p>\n
(a)\u00a0 If one of them is odd, then substitute for the term of even power.<\/p>\n
(b)\u00a0 If both are odd, substitute either of them.<\/p>\n
(c)\u00a0 If both are even, use trigonometric identities to convert integrand into cosines of multiple angles.<\/p>\n
Case-2<\/strong> : When m + n is a negative even integer.<\/p>\n
In this case the best substitution is tanx = t.<\/p>\n<\/blockquote>\n\n\n
Example : <\/span> Evaluate \\(\\int\\) \\(sin^3xcos^5x\\) dx<\/p>\n
Solution : <\/span>We have \\(\\int\\) \\(sin^3xcos^5x\\) dx,
Put cosx = t; -sinx dx = dt
\n so that I = – \\(\\int\\) \\((1 – t^2).t^5\\) dt
\n = \\(\\int\\) \\((t^7 – t^5)\\) dt = \\(t^8\\over 8\\) – \\(t^6\\over 6\\) = \\(cos^8x\\over 8\\) – \\(cos^6x\\over 6\\) + C
\n <\/p>\n\n\n\n(ii)<\/strong>\u00a0 \\(\\int\\) \\(dx\\over {a + bsin^2x}\\) OR \\(\\int\\) \\(dx\\over {a + bcos^2x}\\) OR \\(\\int\\) \\(dx\\over {asin^2x + bsinxcosx + ccos^2x}\\)<\/p>\n
Divide Numerator and Denominator by \\(cos^2x\\) & put tanx = t.<\/p>\n<\/blockquote>\n\n\n
Example : <\/span> Evaluate : \\(\\int\\) \\(dx\\over {(2sinx + 3cosx)}^2\\)<\/p>\n
Solution : <\/span>Divide numerator and denominator by \\(cos^2x\\)
\n \\(\\therefore\\) I = \\(\\int\\) \\(sec^2x dx\\over {(2sinx + 3cosx)}^2\\)
\n Let 2tanx + 3 = t, \\(\\therefore\\) 2\\(sec^2x\\) dx = dt
\n I = \\(1\\over 2\\) \\(\\int\\) \\(dt\\over {t^2}\\) = -\\(1\\over 2t\\) + C = -\\(1\\over {2(2tanx+3)}\\) + C
\n <\/p>\n\n\n\n(iii)<\/strong>\u00a0 \\(\\int\\) \\(dx\\over {a + bsinx}\\) OR \\(\\int\\) \\(dx\\over {a + bcosx}\\) OR \\(\\int\\) \\(dx\\over {a + bsinx + ccosx}\\)<\/p>\n
convert sines and cosines into their respective tangents of half the angles and put tan\\(x\\over 2\\) = t<\/p>\n
In this case sinx = \\(2t\\over {1+t^2}\\), cosx = \\({1-t^2}\\over {1+t^2}\\), x = 2\\(tan^{-1}t\\); dx = \\(2dt\\over {1+t^2}\\)<\/p>\n
(iv)\u00a0<\/strong> \\(\\int\\) \\(acosx + bsinx + c\\over {pcosx + qsinx + r}\\)<\/p>\n
Express Numerator = a(Denominator) + b\\(d\\over dx\\)(Denominator) + c & proceed.<\/p>\n<\/blockquote>\n
Hope you learnt integration of trigonometric function, learn more concepts of integration and practice more questions to get ahead in competition. Good Luck!<\/p>\n\n\n