(vi.)
| ∫ | dx | = log (tan x + sec x). |
| cos x |
(vii.) ∫ eax sin (bx + α) dx = (a2 + b2)−1 eax {a sin (bx + α) − b cos (bx + α) }.
(viii.) ∫ sinm x cosn x dx can be reduced by differentiating a function of the form sinp x cosq x;
| e.g. | d | sin x | = | 1 | + | q sin2 x | = | 1 − q | + | q | . | |
| dx | cosq x | cosq−1 x | cosq+1 x | cosq−1 x | cosq+1 x |
Hence
| ∫ | dx | = | sin x | + | n − 2 | ∫ | dx | . |
| cosn x | (n − 1) cosn−1 x | n − 1 | cosn−2 x |
(ix.)
| ∫1/2π0 sin2n x dx = ∫1/2π0 cos2n x dx = | 1·3 ... (2n − 1) | · | π | , (n an integer). |
| 2·4 ... 2n | 2 |
(x.)