What are Paired abbreviations in angle brackets called?

1).angle is nothing but the deviation among two points. when two points are lie on a same line those two points are said to be collinear.that means the angle between them is 180 because they lie...

angle of incidence!

Because it isn't wrong;) No. It is literally saying that because the angle is perfect, the angle isn't wrong, it is a right angle, it is considered right or true. The word "right" is used for this...

To distinguish it from an acute angle, an obtuse angle and a reflex angle.

A obtuse angle is called an obtuse angle because if obtuse means bigger in degrees and a right angle is 90 degrees than a obtuse angle must be over 90 degrees.