To: Teacher2Teacher Public Discussion
Geometry may be about proof to some extent but one should just look at man made structures to see the uses of geometry. For example, a triangle is completely determined by the length of the three sides. It will not change shape under normal circumstances. A strong bridge, roof, or other structure is not strong unless it has lots of triangles. I once knew a man who built a house of his own design and he failed to put beams all the way across the house and only relied upon a loft to provide strength. In time, the walls started pushing out and the roof was slowly collapsing. This had to be corrected by tying the walls together with beams which formed triangles. As a kid, I used to nail 4 sticks together with one nail at each corner. Guess what, the contraption collapsed and pinched my fingers. Do the same thing with three sticks, and it will not do that. Three points determine a plane. So, that is why milk stools are often equipped with only three legs. The stool won't rock. Four points on the other hand will result in the table rocking. You have probably noticed that when you ate at a four legged table and it rocked badly. Next time you take a trip, try to notice all the triangles in use today. Of course this all relates to vectors with horizontal and vertical components. Elementary physics (mechanics) depends upon this knowledge. In trigonometry, one often determines the Horizontal and vertical components using cosines and sines. Knowledge of geometry helps with that understanding.
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