The expression sin 50 cos 40 + cos 50 sin 40 is equivalent to

Sin (a+b) = sin a. cos b + cos a. sin b

a= 50° and b=40°, then

sin(50+40) = sin 50° . cos 40° + cos 50° . sin 40°

sin(50+40) = sin 90° = 1 and

sin 50° . cos 40° + cos 50° . sin 40° = 1

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.