Circle with straight lines I'm attempting to make a circle with straight lines (in the picture) - I need it to remain whole.
Any advice on how to go about this? The bisector tool kept saying 'error: selected edges/faces required', but I've seen people cutting it by simply dragging across before?
You could try a UV Sphere with a Cast modifier set to Cuboid.

Moving the Subdivision Surface modifier before or after Cast will give different results, and the Factor affects how concave/convex the resulting mesh will be.