Two sides of a triangle measure 15 inches and 18 inches, respectively. Which of these is not a possible length for the third side of the triangle?

Really need on these. i have no idea what to do

3. find the radius of circle p.4. find y.

Lindsay used two points, (x,y; ) and (+2.82), to find the equation of the line, y = mx + b, that passes through the points. y2-y, first, she used the definition of slope and determined that the value of mis x, - . given this information, which expression must represent the value of b?