Question

If you bisect an obtuse angle you get two obtuse angles.

Answer 1

bisect 100

Answer 2

nope

Answer 3

It depends on if you allow angles bigger than 180°. Then you could bisect say 200° and you would get two 100°, obtuse angles. If you don't allow them you can't, since the biggest angle would be 180°, which when bisected leaves two right angles.

Answer 4

It depends on if you allow angles bigger than 180°. Angles greater than 180º are called reflex
see http://www.mathsisfun.com/reflex.html