What is the best way to: what is a right angle

OPT:
(1). In geometry and trigonometry, a right angle is an angle of exactly 90 (degrees), corresponding to a quarter turn. If a ray is placed so that its endpoint is on a line and the adjacent angles are equal, then they are right angles.;
(2). In geometry and trigonometry, a right angle is an angle of exactly 190 (degrees), corresponding to a quarter turn. If a ray is placed so that its endpoint is on a line and the adjacent angles are equal, then they are right angles.;
Answer:
(1).