Microphones are often designed to focus on receiving sounds from certain directions. For example, a cardioid microphone
focuses on capturing sound from the front of the microphone, whereas an omnidirectional microphone
is designed to capture sound from all directions equally. In the two microphone polar patterns above, a fixed sound pressure level at any point on the graph will produce a constant output level from the microphone at the origin. Which equation would best fit a cardioid microphone's polar pattern?