00:03
In this problem, we're going to find the quadratic tailor polynomial for cosine x, cosine y at zero zero.
00:10
And then we're going to estimate the error that we would make using this polynomial for a point near to zero.
00:19
So first we're going to need the derivatives.
00:21
Oops.
00:27
Minus sine x, cosine y, minus cosine x, sine y, minus cosine x, sine y, minus cosine x, sine y, minus cosine x, cosine y, minus cosine x, cosine y, minus cosine x, cosine y.
00:46
Sine x, sine y, minus cosine x, cosine y.
00:56
Now plug in 0, 0, remember cosine of 0 is 1, sine of 0 is 0.
01:02
So you get 1, 0, 0, negative 1, 0, negative 1.
01:13
Now write the taylor polynomial.
01:17
So the constant plus 0x and 0 y, plus 1 over 2 factorial.
01:28
Times minus x squared plus 0 times 2x y minus y squared.
01:37
So that's the taylor polynomial, the quadratic taylor polynomial.
01:43
So now we want to see what sort of error we are making using that.
01:48
So you start the error, this exact same way as if you are finding the next term...