acute angle 锐角acute triangle 锐角三角形adjacent angle 邻角alternate angle 错角alternate exterior angle 外错角alternate interior angle 内错角altitude 顶垂线angle of a circumference 圆周角angular bisector 角等分线arc 弧arc cosine 反余弦arc sine 反正弦arc tangent 反正切axis of symmetry 对称轴base 底线broken line 折线center of a circle 圆心center of figure 垂心、形心central angle 圆心角central symmetry 中心对称centroid 垂心、形心chord 弦circle 圆circular conical surface 圆锥面circular measure 弧度制circumcircle 外接圆circumference 圆周circumscribed circle 外接圆common tangent 公切线complementary angle 余角concave polygon 凹多边形concave polyhedron 凹多面体concentric circles 同心圆cone 圆锥convex polygon 凸多边形convex polyhedron 凸多面体corresponding angle 同位角cosecant 余割cosine 余弦cotangent 余切coversine 余矢cross section 截面cuboid 长方体curved surface 曲面cylinder 圆柱体cylindrical surface 圆柱面degree measure of an angle 角度制degree of an angle 角度diagonal 对角线diameter 直径dihedral angle 二面角distance 距离、距dodecahedron 十二面体double angle 倍角edge 棱ellipse 椭圆ellipsoid 椭圆end point 端点equilateral triangle 等边三角形、正三角形Eulers formula 欧拉公式excentre 旁心exterior angle 外角exterior angles on the same side 同旁外角face angle 面角foot of a perpendicular 垂足foundations of geometry 几何学geimetrical element 几何元素generatrix 母线generator 母线geometric construction 几何作图geometric figure 几何图形half angle 半角half line 半线hexahedron 六面体horizonal line 水平线icosahedron 二十面体incentre 内心incircle 内切圆ineterior on the same side 同旁内角initial side of anangle 角的始边inscribed circle of a triangle 三角形内切圆interior angle 内角interpolation 插值法，内推法intersecting lines 相交线intersection of two lines 两线相交intersection point 交点inverse cosine 反余弦inverse sine 反正弦inverse tangent 反正切inverse trigonometric function 反三角函数isosceles trapezoid 等腰梯形isosceles triangle 等腰三角形lateral face 侧面law of cosines 余弦定理law of sines 正弦定理law of tangents 正切定理line 线line segment 线段median line 中线Napiers rules 纳皮尔定律negative angle 负角oblique spherical triangle 斜角球面三角形obtuse angle 钝角obtuse triangle 钝角三角形octahedron 八面体orthocentre 垂心parallel lines 平行线parallelogram 平行四边形pentagon 五边形pentahedron 五面体periodicity of functions 函数的周期性perpendicular 垂线perpendicular bisector 中垂线plane 平面plane trigonometry 平面三角学plane angle 平面角point 点point of intersection 交点point of tangency 切点polar triangle 极三角形pole of a circle 圆的极点polygon 多边形polyhedral angle 多面角positive angle 正角primitive angle 原始三角形principal value 主值prism 棱柱体pyramid 棱锥体Pythagorean theorem 勾股定理quadrant 象限quadrantal triangle 象限球面三角形quadrilateral 四边形radian 弧度radius 半径ray 射线reciprocal function 互反函数rectangle 长方形、矩形rectangular solid 长方体regular dodecahedron 正十二面体regular icosahedron 正二十面体regular octahedron 正八面体regular polygon 正多边形regular prism 正棱柱rhomboid 长菱形rhombus 菱形right angle 直角right parallelepiped 直平行六面体right prism 直棱柱roots of unity 单位根round angle 周角scalene triangle 不等边三角形secant 正割secant 割线segment of a circle 弓形segment of a circle 弓形semiciecle 半圆圆周率side 边sine-cosine law 正弦余弦定理small side 勾solid angle 立体角sphere 球spherical angle 球面角spherical degree 球面度spherical surface 球面spherical tight triangle 球面直角三角形spherical triangle 球面三角形spheroid 球体square 正方形straight angle 平角straight line 直线supplementary angle 补角surface 面surface of an angle 球面tangent 正切tangent line 切线terminate side of an angle 角的终边tetrahedral angle 四面角tetrahedron 四面体trapezoid 梯形triangular prism 三棱柱trigonometric equation 三角方程trigonometric function 三角函数trihedral angle 三面角trisection of an angle 三等分角versed cosine 余矢versed sine 正矢versine 正矢vertical 垂线vertical angles 对顶角