an angle
a rainbow 
Yes. Any two rays which have the same end point.
An angle.
An angle!
Two collinear rays with the same endpoint form an angle. They share a common initial point and extend in opposite directions. The endpoint where they meet is called the vertex of the angle.
an angle
Angle
Angle
a rainbow 
Yes. Any two rays which have the same end point.
angle
An angle.
An angle!
if the rays have no common points, the answer is zero. if the rays all have the same end point, the answer is 21 -- counting only the acute angles.
A line
angle