You can use the Rotation transformation for that. You can either rotate all shapes (default) or only the selected ones. To select the shapes you need to rotate:
- Activate the Rotation transformation
- Tap the Transformation button on the app title bar and uncheck the shapes you don't want to be rotated
A rotation circle will appear on the screen. Just grab the right most point on the circle and drag it to define the rotation angle. You can also move the entire circle by dragging its center point to change the center of the rotation.
← How do I rotate a geometric shape?