right-angled triangle
noun🔊/ˌraɪt æŋɡld ˈtraɪæŋɡl/
🔊/ˌraɪt æŋɡld ˈtraɪæŋɡl/
(especially British English) (North American English usually right triangle)
a flat shape with three straight sides and one right angle 直角三角形 
