An inflection point is a point on a curve at which the sign of the curvature (i.e., the concavity) changes. Inflection points may be stationary points, but are not local maxima or local minima. For example, for the curve plotted above, the point is an inflection point. The first derivative test can sometimes distinguish inflection points from extrema for differentiable functions . The second derivative test is also useful. A necessary condition for to be an inflection point is . A sufficient condition requires and to have opposite signs in the neighborhood of (Bronshtein and Semendyayev 2004, p. 231).
Rice vermicelli are thin rice-flour noodles common in Chinese, Thai, Vietnamese, and other Southeast Asian cuisines, where they are often used in stir-fries, soups, spring rolls, and salads. Don't confuse rice vermicelli with cellophane noodles, another thin Asian noodle that's made with mung bean starch.
Vermilion is a deep, brilliant shade of red. You could describe your grandfather's reddish-orange scarf as vermilion. The specific pigment know as vermilion was originally made from mercury sulfide, a chemical compound that produces a deep red color. This kind of vermilion was most famously used in enameled Chinese lacquerware. However, you can use the word vermilion to describe anything that's a particularly deep, rich shade of red. The root word is the French vermeil, bright red, from the Latin vermiculus, a little worm, or the insect that was historically used to make red dyes. Definitions of vermilion.