Примери за използване на Cosine theta на Английски и техните преводи на Български
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That is b cosine theta.
Well, we came up with x is equal to r cosine theta.
So sine over cosine theta, I think we learned that already.
That would be b cosine theta.
So this is going to be-- let me write itin a different color. x is r-- so now we're dealing with Cartesian coordinates-- r cosine theta.
Хората също превеждат
It equals b cosine theta.
Multiply both sides by r andyou get x is equal to r cosine theta.
Dot product, cosine theta.
Something should be jumping out at you, andthat's plus c squared minus 2bc cosine theta.
So it's plus c minus b cosine theta squared.
And now I'm going to introduce a new trig ratio,it's really just 1 over cosine theta.
So this vector right here is a cosine theta; the magnitude of a cosine theta.
So this coordinate, x is equal to r cosine theta.
Well if this vector right here is a cosine theta-- and you learned this when you learned how to take the components of vectors.
The magnitude of b cosine theta.
So 1 over cosine theta-- and I'm going to summarize this at the end, just so it's not too confusing-- is actually the secant of theta.
It's just 1 over cosine theta.
Well, if we take this term and this term, we get-- those two terms are b squared sine squared of theta plus b squared cosine-- this should be squared there, right, because we squared it. b squared cosine squared of theta,and then we have plus c squared minus 2bc cosine theta.
I just multiply it out. c squared minus 2cb cosine theta plus b squared cosine theta, right?
So we could factor out an r, so you get r times 3 sine theta minus 7 cosine theta, right?
I know it can be a little overwhelming initially, just because I'm, you know, throwing out all these new terms,secant is 1 over cosine theta, but once you just play around with these enough and get familiar with the terms, it will make sense, and it will be a little more natural to you.
If sine theta equals three fifths, what is cosine theta?
So to do this I have set up a little chart for theta, cosine theta, and sine theta. .
And we can use this and the unit circle to hopefullyquickly graph what the graphs of y equals sine theta and y equals cosine theta are.
So if you were to draw a perpendicular line here,b cosine theta would be this vector.
And we also learned that y is equal to r sine of theta, andx is equal to r cosine theta.
So when you're taking the dot product, at least the example I just did,if you view it as the magnitude of a times the magnitude of b cosine theta, you're saying what part of b goes in the same direction as a?
These are all scalar quantities,so it doesn't matter what order you take the multiplication in. And a cosine theta is the same thing.
That's the same thing as sine of theta over cosine of theta squared plus this is 1 over cosine theta squared, right?
So sine squared theta over cosine squared theta is tan squared theta, then plus1 is 1 over cosine theta squared.