Tan α cotα =1sin α CSC α =1cos α secα =1quotient relation: sin α/cos α = tan α = sec α/CSC α cos α/sin α = cot α = CSC α/secα square relation: sin 2 (α =/kloc) +tan 2 (α) = sec2 (α)1+cot2 (α) = CSC 2 (α) Two common proofs: sin 2 (α)+cos 2 (α) = (Sina-sin θ) = sin (a+θ) * sin (a-θ) COS[(a-θ)/2]SIN(a-θ+) slope formula We usually refer to the ratio of the vertical height h to the horizontal height l of the slope as the slope (also called the slope ratio), which is expressed by the letter I, that is, I = h/L. If the angle between the slope and the horizontal plane is recorded as a (called the slope angle), then i=h/l = tana.