Monday, October 05, 2009

Trig. Finding Sin and Cos of an Angle

I put this in both tech help and personal. It doesn't have anything to do with tech really, but it's help, and my tech help section is looking a little empty.

So my trig class has already moved on to sum and difference formulas, as well as half angle formulas. But one of the things I have failed to grasp up til this point, was the basic sin and cos of a basic angle such as 45 degrees. I can tell you that the sin of 45 degrees is (root)2/2, just cause I see it so often. I could survive without having it memorized, the calculators we use can do this kind of thinking, and they are essential for everything in that class. But, the calculators themselves can be tricky and it could take more time to solve by calc, than it is to spit out something memorized. So this brings me to a table I'd like to share with you, that was never shown in my class, for all basic angles in the 1st quad

30 degrees45 degrees60 degrees
all divided by 2

This table with some manipulation, can get you almost all major angles. For example, the sin of 60 degrees by using this table, would get you (root)3/2. Well how about the sin of 120 degrees. It's the same angle as 60 degrees, just in the second quad. So the answer would be -(root)3/2.

Anyways I felt this table was very helpful, and I will be using it for sure in my math class.

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