The stationary waves set up on a string have the equation y = (2 mm)sin[(6.28 m^-1 )x] cos(ωt). This stationary wave is created by two identical waves, of amplitude A each, moving in opposite directions along the string.

(a) A = 2 mm 

(b) A = 1 mm 

(c) The smallest length of the string is 50 cm. 

(d) The smallest length of the string is 2 m.