A closed circle means that value is included, and an open circle means that value is excluded.
Example:
x > 2 ---- Graphed with an open circle, everything greater than but not including 2
x ≤ 3 ------ Graphed with a closed circle, everything less than and including 3
If i understood it right when you estimate the quotient it help you have an idea
E because of sss ( side side side)
A sinusoid is cyclical and has a period or frequency.
y = sin x is a sinusoid, with a period of 2π.
y = √x is not a sinusoid.
y = cos x is a sinusoid with a period of 2π.
Answer: y = √x is not a sinusoid.