Why is the value of -9 is not-3

An objects motion is described by the equation d= 4sin (pi t) what will the height of the object be at 1.75 seconds?

Which is the graph of the piecewise function f(x)? f(x)=[tex]f(x) = \left \{ {{-x+1, x\leq 0 } \atop {x+1, x\ \textgreater \ 0}} \right.[/tex]

A(t)=728(1+0.04)^t how much money did aditya originally invest