Plisss jawabbb dong ini pentinggg banget

3. diket : lamda = 40cm = 4000 m
v = 20 m/s
ditan : a. T .....?
b. f......?
jwb:
a. T = v. lamda
= 20 × 4000
= 80000 s
b. f = v/lamda
= 4000/20
= 200 Hz