Solve by the help of the graph

How can you construct perpendicular lines and prove theorems about perpendicular lines

For problems 29 - 31 the graph of a quadratic function y=ax^2 + bx + c is shown. tell whether the discriminant of ax^2 + bx + c = 0 is positive, negative, or zero.

Charlie tosses five coins.what is the probability that all five coins will land tails up.