What can you do with trig? Historically, it was developed for astronomy and geography, but scientists have been using it for centuries for other purposes, too. Besides other fields of mathematics, trig is used in physics, engineering, and chemistry. Within mathematics, trig is used in primarily in calculus (which is perhaps its greatest application), linear algebra, and statistics. Since these fields are used throughout the natural and social sciences, trig is a very useful subject to know.
Trigonometric function
I.1.Laws of sine The sine of an angle is the ratio of the length of the opposite side to the length of the hypotenuse.
Source: http://hyperphysics.phy-astr.gsu.edu/hbase/lsin.html
The cosine of an angle is the ratio of the length of the adjacent side to the length of the hypotenuse.
Source: http://hyperphysics.phy-astr.gsu.edu/hbase/lcos.html#c1
The tangent of an angle is the ratio of the length of the opposite side to the length of the adjacent side.
Source: http://en.wikipedia.org/wiki/Law_of_tangents
II.
Proof
I.
Source: http://www.youtube.com/watch?v=APNkWrD-U1k
Source: http://www.cut-the-knot.org/pythagoras/cosine.shtml
Source: http://en.wikipedia.org/wiki/Law_of_tangents
II.
Magic applet A Java application; an application program that uses the
client’s web browser to provide a user interface
Application
Source: http://www.mathscareers.org.uk/14_-_16/maths_in_everyday_life/trigonometry.cfm
2. Comparison to real life situation
Source: http://itsscrapped.blogspot.com/2008/03/trigonometry-of-love.html
Magic Identity Source: http://www.sosmath.com/trig/magicide/magicide.html
Mnemonics The common use of mnemonics is to remember facts and relationship in trigonometry. For eaxample “SOH CAH TOA ( Some Officers Have Curly Auburn Hair Till Old Age)
Source: http://www.economicexpert.com/a/Trigonometry:mnemonics.htm
Relationship of sine, cosine, and tangent.
Source: http://en.wikipedia.org/wiki/Trigonometric_function
Evaluate yourself by different quizzes. Do it step by step.
