If I understand your question, you are referring to the vertex. This is the point where the sides meet, also where the angle is formed.
It is simply a right angle triangle but if the sides were the same then it is an isoceles right angle triangle
It is an inscribed angle.
Point of view
vertex
They would be intersecting.
Adjacent sides.
The vertex (or apex).
square
It is simply a right angle triangle but if the sides were the same then it is an isoceles right angle triangle
It is an inscribed angle.
It is a perpendicular line that forms a right angle at the point of intersection.
It is the subtended angle of the arc
Point of view
A right angle
vertex
A point, line or curve.
An isosceles triangle