Two waves are superposed. one wave has an amplitude of 3 cm, and the other has an amplitude of 4 cm. what is the resultant amplitude?

The sum (or difference) of two solutions of the wave equation is again a solution of the wave equation(superposition principle)

therefore the amplitude of resultant wave is 3+4= 7cm

The horse latitudes-high-pressure zones about 30 degrees north and 30 degrees south of the equator.-warm air traveling away from the equator cools and sinks-weather tends to be clear and drythe doldrums-low-pressure near equator-air rises and spreads out toward the poles-rising moist air produces clouds and heavy rainthe westerlies-blow from the west-move from the horse latitudes toward the poles.-bring storms across much of the united statesthe tradewinds-blow from the east-move from the horse latitudes toward the equator  -strong, steady winds