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Monday, February 24, 2014

I/D #1: Unit N Concept 7 - How Do Special Right Triangles and the Unit Circle Relate?

Inquiry Activity Summary
1) The first and foremost part of interpreting a 30° special right triangle, is setting the side opposite of the 30° angle to x, and going along with that, the hypotenuse as 2x, and the other leg of the triangle as x3. In order to align this set-up with the unit circle, we must set the hypotenuse equal to 1, since the radius of a unit circle will always be 1, and the hypotenuse will be exactly between the Unit Circle's center and its arc. So, if we set the hypotenuse to 1, then we basically divide all of our previously-acquired values by 2x, making it proportionate to the 2x = 1 ratio that we had fabricated. So, the x would become 1/2, and the x3 would become 3/2.



2) In order to make sense of a 45° special right triangle, we should first set up the hypotenuse as x√2, and the other two sides as x (since both sides are the identical, according to geometry). To match this up with the unit circle, we set the hypotenuse to 1, which is most simply done, by dividing x√2 by x√2, which gives us 1. Dividing x by x√2 would make x times (1 / x√2), creating a situation in which the x's cancel out, and you are left with 1/√2. In order to rationalize that, you would multiply it by (√2 / √2), which would result in (√2 / 2) for your two other sides.



3) Lastly, the 60° special right triangle should include the exact same values as the 30° special right triangle would. All that one would have to do, is ensure that values accordingly match up with degrees. But, I suppose that I have enough time to explain this. Basically, the side opposite of your 60° angle would be set to x3, your hypotenuse set to 2x, and your other leg, set to x. In order to substantiate a hypotenuse equal to 1, you would divide all of the values by 2x, and end up with 1 for the hypotenuse, 3/2 for the side that had previously equaled x3, and 1/2 for the side that had previously been x.



4) How Does This Activity Help You To Derive The Unit Circle?
I suppose that this activity helped me more easily identify all of the values that encompass various common degrees in a unit circle, by listing out all of the possible values that I should know. If I were tasked to find out the coordinates of wherever any 30° or 60° angle's terminal side met with the Unit Circle's arc, there could only ever be three values that I need to know (their signs and or order depend upon which quadrant of the circle they are in): 1, 3/2, and 1/2. For the 45° angle, literally the only two values I would ever need to figure out coordinates of wherever the 45° angle's terminal side met with the unit circle's arc would be 1 and √2 / 2. This stuff is really useful in trigonometry and all.

5) The triangles drawn in this activity were in Quadrant I, ergo, their positive coordinates. The signs would change in differing quadrants, with Quadrant II implying a negative x-coordinate, Quadrant III, a negative x-coordinate and y-coordinate, and Quadrant IV, a negative y-coordinate.



Inquiry Activity Reflection
1) The coolest thing I learned from this activity was that from remembering three simple values (3/2, 1/2, and √2 / 2), you can get everything that you need in the Unit Circle. All you'd have to do is remember what different quadrants do to the signs of the values, and all that other stuff.

2) This activity will help me in this unit because I can now, more easily remember the Unit Circle.

3) Something I never realized before special right triangles and the unit circle is that just by identifying which side is the longest of the two of a 30° or 60° angle, you can determine which has the 3/2, and which is the 1/2 (3/2 is bigger than 1/2).