复数：dihedrals
1.由两个平面构成的,二面的
1.【数】二面角;【航】上反角;下反角
1.the angle contained between two planes that intersect, measured by the angle made by any two lines at right angles to the two planes
2.the angle between an upwardly inclined aircraft wing and a horizontal line
dihedralsdihedralsdihedrals