Greek alphabet is a letter used in Greek, and it is also widely used in mathematics, physics, biology, astronomy and other disciplines. Greek letters are similar to English letters and Russian letters, but with different symbols and the same phonetic properties. α β γ δ θ is a symbol commonly used in mathematics to represent angles. I feel very comfortable when I write and sing, and there are gamma rays. You will encounter λ θ in trigonometric functions. Degree-day at the beginning of κ, μ ν represents indoor focal length, ρ represents density, σ π represents two chemical bonds, where π represents.