If QC is tangent to circle O and QC = 8 and BC = 4, then the length of AB, the diameter, is _?_

One card is dealt from a 52 card deck. find the probability that the dealt card is a 4 or a black 7

Ineed to know the answer to this algebra question.

The boiling point of water at an elevation of 0 feet is 212 degrees fahrenheit (°f). for every 1,000 feet of increase in elevation, the boiling point of water decreases by about 2°f. which of the following represents this relationship if b is the boiling point of water at an elevation of e thousand feet? a) e = 2b - 212 b) b = 2e - 212 c) e = -2b + 212 d) b = -2e + 212