1, acute angle formula of trigonometric function: opposite side/hypotenuse of sinα=∞α.

2. Triple angle formula: sin3α = 4Sinα sin (π/3+α) sin (π/3-α).

3. Auxiliary angle formula: asinα+bcosα = (A2+B2) (1/2) sin (α+t).

4. Power failure formula: sin 2 (α) = (1-cos (2α))/2 = versin (2α)/2.

5. Derived formula: tan α+cotα = 2/sin2α.