In this video I go through a typical exam question where a person is on top a cliff and sees a boat in the water. Typically you are given the height of the cliff and the angle of depression to the boat and are asked to calculate how far the boat is from the base of the cliff.
Credit: Patrick Maye

Congruency and similarity in triangles. More free lessons at: http://www.khanacademy.org/video?v=eF6zYNzlZKQ Note: All Khan Academy content is available for free at (www.khanacademy.org)

Introduction to trigonometry
More free lessons at: http://www.khanacademy.org/video?v=Jsiy4TxgIME
Note: All Khan Academy content is available for free at (www.khanacademy.org)

Worked example using the theorem of Pythagoras to solve a modelled word problem. More free lessons at: http://www.khanacademy.org/video?v=eF6zYNzlZKQ Note: All Khan Academy content is available for free at (www.khanacademy.org)

Introduction and overview of the Pythagorean theorem. More free lessons at: http://www.khanacademy.org/video?v=eF6zYNzlZKQ Note: All Khan Academy content is available for free at (www.khanacademy.org)