Learn more: http://www.khanacademy.org/video?v=CmXmRNFrtFw
More examples of using definite integrals to calculate the area between curves

Length: 8 minutes

Definite integral with substitution

Length: 7 minutes

Integrals: Trig Substitution 1

Length: 8 minutes

Integrals: Trig Substitution 2