Design of both summit and valley curves is based on the assumption that the

• A. curve is so flat that the length of curve is equal to the length of chord
• B. two portions of the curve along the two tangents on either side of the point of intersection are equal
• C. angles made by the tangent with the horizontal are very small and tangents of those angles are equal to the angles themselves (in radians)
• D. all of the above