The function, f(x), is plotted below.

On a coordinate plane, a function curves up to (StartFraction pi Over 4 EndFraction, 0), curves down through (0, negative 0.5) to (StartFraction 3 pi Over 4 EndFraction, negative 4) and then curves back up.

What is reasonable estimate for the limit?

Limit of f (x) as x approaches StartFraction pi Over 4 EndFraction f(x) =