# Doppler Effect frequency

## Homework Statement

source emits sound with a characteristic frequency of 640 Hz. Calculate the observed frequency and the wavelength between source and observer in each of the following situations.
a) The observer approaches a stationary source at 57 m/s
b) Both the source and observer move towards each other at 28.5 m/s

## The Attempt at a Solution

I already managed to calculate for the frequency: 747.29 Hz but can anyone explain to me how to find the wavelength because what i thought was that i could simply do 340/747.29 which is wrong..Help please!

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