Q&A #6237

Teachers' Lounge Discussion: Trigonometry

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From: loyd

To: Teacher2Teacher Public Discussion
Date: 2001071909:16:01
Subject: Trigonometry Uses

Here are some examples:

1.  Three points determine a plane, hence the three legged milk stool
won't rock on an uneven surface.  4 legged table will.

2.  Triangle will hold its shape or else break If you join three
sticks with a nail at each vertex.  Thus, we use triangles for house
building and constructions of all types to make strong structures.
Rectangles will not hold shape if only one nail is used to join the 4
pieces of wood with only one nail at the vertices.  All engineering
courses require a thorough knowledge of trig.

I know a man who built his own house and there were no joists joining
his walls so that it was shaped like this with no triangles:

/  \
|  |

By and by, the walls started spreading apart.  Solution, add joists to
form triangles connected from wall to wall.

3.  Electrical engineering requires trig to understand how motors and
generators work.  The alternating current used in most equipment is a
sinusoid or sine wave.  Trig is required to understand most electrical
engineering problems.  

4.  Mechanical power factor is determined by the cosine of the angle
that is applied to your work.  An example of a good power factor is
when you push a sliding door from the side at 90 degrees vice 0
degrees.  The door doesn't move unless you have an angle less than 90
degrees - poor power factor.  Electrical circuits have also have power
factor but it is a little more abstract which makes it exciting.

4.  Squaring a house, or pyramid requires trig (Pythagorean Theorem).
The 6,8 10 triangle is useful here as well as knowing that a rectangle
has diagonals that are equal.  One can use this method by using a
tape, screwdriver and nails to create arcs when building a house. 
Instead of pencil marks, stick nails in the ground, and with the tape
held at the other end by a large screw driver, you can create an arc
with one diagonal and do the same with another diagonal, and where
they cross is another corner. 


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