ज्ञात करें `int "cosec"^4 x dx`

Explanation

यहां cossec x का घात धन सम पूर्णांक ( even positive integer ) है, इसलिए `z=cot x ` रखे
अब, `int "cosec"^4 x dx = int "cosec"^2x dx`
`=int(1+cot^2x)"cosec"^2 x dx = int (1+z^2)(-dz)=-int(1+z^2)dz`
`=-(z+z^2/3)+c=-cot x -(cot^3x)/3+c`