3D rotation by quaternion

- The quaternion allows rotation about a 3D direction vector, rather than as a combo of rotations about the x, y, & z axes (i.e. Euler rotations). - This worksheet visualizes the direction vector and associated plane of rotation (perpendicular to the vector). - Use the 'Trace' checkbox for greater insight. - The 'Scale...', & 'Set radius...' sliders adjust the unit quaternion. - To orbit in 3D Window, use R-Click. - To see the underlying matrices, etc., download the GGB and look into the Algebra Window. - Check out the Spreadsheet Window for the matrices. *Based on the excellent worksheet by Christopher Coulombe at https://tube.geogebra.org/material/show/id/1140681.