CURVE FORMULAE CURVE TABLE Table of Tangent and External to a 1° Curve To find Tangent and External for curve of any other degree, divide by degree of curve and add correction found in column of corrections. Degree of curve with a given I may be found by dividing tangent, (or external), opposite I by given tangent, (or external). The distance from a point on the tangent to the curve is very nearly the square of the tangent length divided by twice the radius. CURVE FORMULAS Radius: R = 50 / sin(1/2 D) Length of Curve: L = 100 * (Δ/D) also L = .0174533 × Δ × R Degree of Curve: D = 100 * (Δ/L) Tangent: T = R tan(1/2 Δ) Long Cord: LC = 2R sin(1/2 Δ) Middle Ordinate: M = R (1 - Cos(1/2 Δ)) External: E = T tan(1/4 Δ)