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January 28, 2015

January 28, 2015

Posted by **Angela** on Saturday, August 23, 2008 at 12:06pm.

________________<20*

|<90*

y |

|<70*

(hypotenuse length is 12 units)

I'm learning about trig ratios, and my dad was trying to compare it to a circle or something? All I know is

sin = a/c

cos = b/c

tan = a/b

you're trying to figure out the proportions of the lengths of the triangle relative to its angles, actually the other way around in this case.

In accordance with the ratios I listed above,

side A is opposite angle A

side B is opposite angle B

side C is opposite angle C

so, in this case, the right angle is <C and the hypotenuse is side C

thus, does: ?

sin = y/12

cos = x/12

tan = y/x

Now I'm a little confused on how to bring in the angles, and how do I know whether to use sin,cos, or tan?

_______________________________________________

What happens with a problem where I know 2 of the sides, and that it's a right triangle? I then have to figure out the other two angles x and y.

I can figure out the length of the third side using the Pythagorean theorem, but how to I reverse to figure out the angular proportions from the lengths?

Thanks

- Geometry -
**Reiny**, Saturday, August 23, 2008 at 12:32pmyour Dad is making the connection between the "unit circle" and basic trigonometry.

Do a Google search for "unit circle" or "trigonometry and the unit circle"

You will get many webpages, here is one that seems to be quite good

(Broken Link Removed)

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