Why do we study right triangles in trigonometry?

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Discussion Overview

The discussion revolves around the significance of studying right triangles in trigonometry, exploring why they are often preferred over other types of triangles for defining trigonometric functions. The scope includes conceptual reasoning and technical explanations related to trigonometry.

Discussion Character

  • Conceptual clarification
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions the necessity of focusing on right triangles, suggesting that trigonometric functions could be defined for any triangle, such as a 70-degree triangle.
  • Another participant argues that right-angled triangles are the simplest to work with and that trigonometry based on them is sufficient for addressing questions related to non-right-angled triangles.
  • A different viewpoint suggests that any triangle can be divided into two right triangles, making right triangles a practical choice for trigonometric applications.
  • One participant mentions that while other angles could be used, they would result in more complex calculations and potentially require multiple trigonometric tables.
  • Another contribution emphasizes that sine and cosine relate to coordinates on a circle, with right triangles being relevant due to the perpendicular nature of the coordinate axes.
  • It is noted that the Pythagorean theorem applies to right triangles, while the law of cosines, which applies to other triangles, is more complicated.

Areas of Agreement / Disagreement

Participants express differing views on the necessity and efficiency of using right triangles in trigonometry. Some argue for their simplicity and sufficiency, while others question the exclusivity of this approach, indicating that the discussion remains unresolved.

Contextual Notes

Some participants' arguments depend on the assumption that right triangles provide a more straightforward framework for trigonometric functions, while others suggest that alternative approaches could be valid but may lead to increased complexity.

Avichal
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Why do we study so much about right triangles like trigonometry. We could define sin and cos like functions in a 70 degree triangle too.
I also know right triangle is something special but i don't know what is it. Also why won't trigonometry on other type of triangles be not so good
 
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Because right-angled triangles are simplest to start out with.
Furthermore, trigonometry based on that is sufficient to handle all questions you would like to ask non-right-angled triangles, as well. Thus, developing other types of plane trigonometry is unnecessary and a waste of time.
 
If you find yourself working with a lot of 70 degree triangles, or any other number of degrees for that matter, feel free to make a trig table based on that if you feel it will save you time.

Right triangles are preferable as the basis for trigonometry because any other triangle can be cut into two right triangles, by drawing a line through one vertex perpendicular to its opposite side. While you could, in this day and age of analytic geometry, draw a 70 degree angled line just as well as a perpendicular, the two triangles you got from that would have one with a 70 degree angle and the other with a 110 degree angle. So, you would need two trig tables to sort it all out (or a messy set of successive approximations).

Also, when you get to unit circle trig (if you haven't already), the right triangle definition correlates with the coordinates of a point on a grid in a way that is very neat and easy to see and use. You could come up with a formula based on other angles, but it would be much messier and harder to use.
 
sin and cos have not so much to do with triangles, they are the coordinates of points on the circle. the right triangles come in because the coordinate axes are perpendicular to each other.

The reason we use perpendicular axes, or right triangle trig, is the pythagorean theorem. The pythagorean theorem for other triangles is called the law of cosines and is more complicated.
 

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