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Trigonometry is a branch of mathematics that studies relationships between side lengths and angles of triangles. Usually, to find the length of a missing side of a right triangle, you would need to have the length of the other 2 sides and then use Pythagorean's Theorem. Trigonometry makes it possible to find the side length (or angle measure) of a right triangle without using Pyth. Thm.
There are three basic functions in trigonometry, each of which is one side of a right-triangle divided by another. It is helpful to remember Sine, Cosine and Tangent as SOH CAH TOA.
The key is to remember that each of these is a function, a relationship between the input (the angle) and the output (the ratio of the sides)
PRACTICE:
ANSWERS TO PRACTICE QUESTIONS:
cos 60 =1/2
tan 60 = 1.732
sin 0 = 3/5
cos 0 = 8/17
sin 0 + cos 0 = 31/25
The Law of Sin and The Law of Cos can be used if you are finding the side length (or angle measure) of ANY triangle - not just a right triangle.
USING TRIGONOMETRY TO FIND AREA OF POLYGONS
USING TRIGONOMETRY TO FIND AREA OF POLYGONS
Think about what you know and why is the side of the triangle 3"?
Why use the tan function and nor sin or cos?
EXAMPLE:
Given a regular hexagon with a side measuring 6", find the area.
SOLUTION: HINTS
Recall the formula for the interior angle amount of any polygon: S=180(n-2) where n is the number of sides.
Now get each angle measure
SInce the radius bisects the angle, you have the measure of the small angle in the triangle.
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