HOW SINES AND COSINES WORK
#Trig #Trigonometry #Sine #Cosine
You have understood sines and cosines since you were two years old; you just didn't know the terminology.
Let us start with a diagonal line; a slash will do:
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Now, do you agree that the line travels up and to the right? (Of course you do.) Do you also have a sense that the amount of "up" and the amount of "right" is related to the angle? (I imagine you do.)
The "sine" is just how much "up" you get with a given angle. and the "cosine" is how much "right" you get with an angle. Sines and cosines range from -1 to 1; when they're negative, you can think of them as "down" and "left" respectively.
That's all sine and cosine are: they tell you how far vertically and horizontally you go for a given angle. And as promised, you knew that even as a toddler: steep angles go up a lot, gentle slopes do not.
You can also think of sines and cosines as percents, that go from -100% to 100%. People don't do that in common practice, but you can think in those terms if it makes things feel more right. For example, the sine of a 30-degree angle is 0.5, OR you can think of it as 50%. So if you draw a 10 inch line at a 30 degree angle, that line will end up 5 inches up from where you started: 50% of 10 inches is 5 inches.