Definition of right angle in English:
right angle
Syllabification: right an·glenoun
 An angle of 90°, as in a corner of a square or at the intersection of two perpendicular straight lines.More example sentences
 It follows that on the earth's surface there is an equilateral triangle with all its angles equal to a right angle.
 Give to a philosopher the concept of a triangle, and let him discover in his own way what the relation of the sum of its angles to a right angle might be.
 He also designed an instrument to divide a right angle into a given number of equal parts.
Phrases

at right angles (or a right angle) to
 Forming an angle of 90° with (something): hold the brush at right angles to the surfaceMore example sentences
 He does it again and much more noticeably in the way he tilts numbers of squares of both kinds until one of them in the middle lies at right angles to all the others.
 A hundred yards away, a sorry looking BMW 6series is parked at right angles to a motorway barrier, forming a makeshift roadblock.
 Ball number six was nicely played back to the bowler amid the huge West Country sigh of relief, and then came the horrified realisation that the umpire's arm was at right angles to his body.