Which is the best definition for a trapezoid?
a.
a quadrilateral with no equal angles
b.
a quadrilateral with just 1 pair of parallel sides
c.
a parallelogram that can have 2 equal angles
d.
a parallelogram with no sides equal

It's letter B 
a quadrilateral with just one pair of parallel sides

Period is the time it takes for one “cycle” to complete. in the parent sine function, period is 2*pi since sin(0) = 0, sin(pi/2) = 1, sin(pi) = 0, sin(3pi/2) = -1, and sin(2pi) = 0. at that point, the sequence repeats itself. i’m not sure if your graph is similar to the sine function since you didn’t provide a picture, but you can find the period by looking at a graph.