[填空题]
An unfingered guitar string is ih pdaf;gli5m,cj020jc m /b7v+xw xzxk 3qarud3: x k-1eq0- 0.73 m long and is tuned to play E above middle C (330wq3-3kd x -+0zx:vq xuer a1kx Hz).
(a) How far from the end of this string must the finger be placed to play A above middle C (440 Hz)?$\approx$ m
(b) What is the wavelength on the string of this 440-Hz wave? $\approx$ m
(c) What are the frequency and wavelength of the sound wave produced in air at 20°C by this fingered string? Hz m