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Mathematics 20 Online
OpenStudy (anonymous):

HELP! http://gyazo.com/e7bc4de262daa0a9da272702ba995677

OpenStudy (theeric):

Have you done problems like this in class?

OpenStudy (anonymous):

no homeschooled for this year (well online school)

OpenStudy (theeric):

Okay. I was just wondering how you were allowed to decide the answer: whether you can use a picture, or if you have to prove it with numbers. The picture is easier, the numbers are more certain.

OpenStudy (theeric):

Do you know the definition of ech kind of triangle?

OpenStudy (anonymous):

no

OpenStudy (theeric):

Alright! That's an excellent place to start, then.

OpenStudy (anonymous):

ya so is openstudy.com

OpenStudy (theeric):

|dw:1348944362708:dw|Let's start with the keyword "right". "Right" means that two of the sides meet at a right angle, a 90 degree angle.

OpenStudy (anonymous):

ya

OpenStudy (theeric):

So when you see a right angle in a triangle, you're looking at a "right triangle".

OpenStudy (theeric):

Do you understand that part?

OpenStudy (anonymous):

ya

OpenStudy (theeric):

Cool. Moving on.... There's also the keyword "obtuse". "Obtuse" is a keyword that indicates the angle too, but this time there must be an angle that is greater than a right angle, greater than a 90 degree angle.

OpenStudy (anonymous):

yes

OpenStudy (theeric):

So if you see an obtuse angle, then you're looking at an obtuse triangle.

OpenStudy (theeric):

Now, what's left are the keywords "scalene" and "isosceles". "Equilateral" is another, but you don't need to know that right now, I guess!

OpenStudy (anonymous):

ok

OpenStudy (theeric):

These tell you how the lengths compare to each other. Scalene: no lengths are the same Isosceles: 2 lengths are the same Equilateral: all 3 lengths are the same

OpenStudy (theeric):

Do you understand those?

OpenStudy (anonymous):

ya

OpenStudy (theeric):

Cool! Now you can either draw the triangle on a grid and look to see what it looks like, or find all of the triangles' sides lengths.

OpenStudy (theeric):

Do you know how to use two points to mathematically find the length of the line segment that connects them?

OpenStudy (theeric):

The formula is messy looking, but very precise and I can tell you how to get it exactly if you want. Let d be the distance between the points\[(x_1, y_1)\]and\[(x_2, y_2)\]. Then.......

OpenStudy (theeric):

\[d=\sqrt{(x_2-x_1)^2+(y_2-y_1)^2}\]

OpenStudy (theeric):

You can pick any given point to be\[(x_1, y_1)\] and any other given point to be \[(x_2, y_2)\]

OpenStudy (theeric):

But lets's try graphing first. That isn't "solid evidence", you know, but we can make good guesses with our choices! Drawing!....

OpenStudy (theeric):

Good luck! It helps to make a grid and plot your triangles on there. I've got to go! Take care!

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