spherical AOB = 30° angle ∟ right angle = 90° = 90° α ° 1 turn = 360° = 60° degree α deg 1 turn = 360deg = 60deg degree α ′ prime arcminute, 1° = 60′ = 60°59′ α ″ = 60°59′59″ double prime arcsecond, 1′ = 60″ α line infinite line AB line segment line from point A to point B ray line that start from point A arc arc from point A to point B = 60° AC BC ⊥ perpendicular lines (90° angle) ⊥ r | | parallel parallel lines AB | | CD congruent to equivalence of geometric shapes and size ∆ABC≅ ∆XYZ ≅ ~ similarity same shapes, not same size ∆ABC~ ∆XYZ Δ triangle triangle shape ΔABC≅ ΔBCD | x-y | = 5 distance distance between points x and y π c = = 2⋅π⋅r pi constant = 3.141592654... π⋅d π
spherical angle AOB = 30° ∟ right angle = 90° α = 90° ° degree 1 turn = 360° α = 60° deg degree 1 turn = 360deg α = 60deg ′ prime arcminute, 1° = 60′ α = 60°59′ ″ double prime arcsecond, 1′ = 60″ α = 60°59′59″ line infinite line AB line segment line from point A to point B ray line that start from point A arc arc from point A to point B = 60° ⊥ perpendicular lines (90° angle) AC ⊥ BC | | parallel parallel lines AB | | CD ≅ congruent to equivalence of geometric shapes and size ∆ABC≅ ∆XYZ ~ similarity same shapes, not same size ∆ABC~ ∆XYZ Δ triangle triangle shape ΔABC≅ ΔBCD distance distance between points x and y | x-y | = 5 π pi constant π = 3.141592654... c = π⋅d = 2⋅π⋅r r
basic_math_symbols.docx