Can you please solve these equations and explain them for me.

13. Evaluate / sincosadr by four methods: (a) the substitution u = cos I. (b) the substitution u = sinr. (c) the identity sin 2x = 2 sin I COS I. (d) integration by parts. 14. Evaluate the following integrals analytically. (a) sin' reos' r dr (b ) sin t cost t dt *#/4 (c) sec' ttan't dt (d) tan't sect dt (e) I' sina da (1) (2 3 + 4x' + 1 - 3)e-' dr (8 ) / $2" ds (b ) - (In a ) dr 23 " Vilnidr (k) cos' 2r sin' 2r dr (h) sec'r tan- r di