Hi

You need to go to:

Preferences/Configure Cura/settings

In the category "infil" you will find "infil line direction"

After selecting it it will appear in the basic configuration menu and you will be able to input the infil angle.

Ray Tahir Mushtaq, I would like to know whether u want to print the model in the respective angle. If yes means while modelling the beams, have a supporting member at the angle of 45 degrees to the base plate and then convert it into STL file.

Here's how you can adjust the infill angle independently of the build orientation:

For more info, visit https://support.ultimaker.com/hc/en-us/articles/360012607079-Infill-settings

Hold the model by pressing right mouse button then rotate in the desired angle.