Can someone help me with these two problems. Thanks a lot.

1. integral of cos^3 thelta sin thelta d thelta, u= cos thelta

this is what I did so far: du/dx= -sin thelta du= -sin thelta dx => -du=sin thelta d thelta ...I dont even know if this is correct. I need to sub. u into the function but dont know how.

2. integral sec^2(1/x)/x^2 dx , u = 1/x

I got -ln x du = dx .....I dont know what to do at all