How are periodic phenomena relatively easy to model using trigonometric functions? what makes them difficult to model this way? explain your
reasoning .

1- what do you think the product of a nonzero rational number and an irrational number is? is it rational or irrational? make use of variables, the closure property of integers, and possibly a proof by contradiction to prove your hypothesis.2- why do we have to specify that the rational number must be nonzero when we determine what the product of a nonzero rational number and an irrational number is? if the rational number were 0, would it give us the same result we found in the first question?

Which of the following parabolas opens down?

What value is a discontinuity of x squared plus 8 x plus 4, all over x squared minus x minus 6?