and then solvefor
from whichwe get and
So the upperand lowerboundariesintersectat points and
As you can see fromthe graph, and hence and in the interval
Applyingthe area formula,
A
Integrating,
A
So the area betweenthe two curves and is
Sometimesit is possibleto applythe area formulawith respectto the -coordinatesinsteadof the -co-
ordinates.In this case,the equationsof the boundarieswill be writtenin sucha way that is expressed
explicitlyas a functionof (Figure3).