periodicity of f(x)=2sin(pi/2 x)
We save the definition: f(x) = 2·sin(π2·x)
Let's find the smallest positive period of 2·sin(π2·x)
The period of sin(x) is 2π; for a·sin(bx + c) + d, we obtain T = 2·πabs(b). The nonzero factor a and the shifts c and d do not change the period.
The coefficient of x in πx2 is π2
T = 2ππ2
T = 2π·2π
T = 4ππ
T = 4
▶Period:   4