What does concave mean

Prove that quadrilateral is a rhombus.

The number of calories you burn depends on your weight. a 110-pound person burns 163 calories during 30 minutes of tennis. find the number of calories that a 190-pound person would burn during the same activity, assuming they burn calories at the same rate.

If p(a) = 0.70 and p(b) = 0.20, then a and b are independent events if