dunno how to simplify this further, i trapped myself !
@robjohn how to dissociate $D$ from $cos(\theta+D)$ and $sin(\theta+D)$ in this equation
we would have been driven to $sin(D)$ and $cos(D)$ this is bilateral equation need to be unified in terms of D, means $sin(D)$ and $sqrt(1-sin^2(D))$, oh darn, i hope things wont get worse than a quadratic equation.
The exact problem I am looking at is: http://math.stackexchange.com/questions/1469454/taylor-expansion-bound
I am asking this because in my notes there is the inequality $$|\delta_{h,r}f(x)- f''(x)| \leq \frac{11}{12} h^2 ||f^{(4)}||_{\infty}$$ and I tried to prove it on my own. Do we maybe conclude to that in an other way? @robjohn
@Agawa001 there are crazy popular questions that get overly saturated on some social medium somewhere and get tons of votes. Questions that are not really that mathematically interesting or difficult, but they get a lot of attention since the question grabs a lot of people's attention.
@DeMoivre they don't define a field structure on $F\times F$
@Karim Eric's answer on the original seemed to answer the question more to me
@MikeMiller @TedShifrin Either of you know how the accidental isomorphisms Spin(5)=Sp(2) and Spin(6)=SU(4) work? I know the ones for Spin(k) for k=1,2,3,4. Also, in Wikipedia's article on spin groups, what does it mean by "there are certain vestiges of these isomorphisms left over for n = 7, 8"? Is that the triality thing mentioned on the Spin(8) page?
