Trigonometry

Trigonometric identities of half angles

Keywords: trigonometric identities of half angles

s i n 2 α 2 = 1 c o s α 2
c o s 2 α 2 = 1 + c o s α 2
t g α 2 = 1 c o s α s i n α = s i n α 1 + c o s α
c t g α 2 = 1 + c o s α s i n α = s i n α 1 c o s α