# \startformula

## Syntax

 \startformula ... \stopformula

## comment

Note: these are defined by the following lines in core-mat.tex:

 \setvalue{\e!start\v!formula}{\dostartformula{}}
\setvalue{\e!stop \v!formula}{\dostopformula}


## Example

 \starttext 

This is the first mathematical formula 

\placeformula[First] \startformula \sin^2(t)^2 + \cos^2(t) = 1. \stopformula This is another formula \placeformula[eqn:tangent] \startformula \cos^2(t) = \frac{1}{1+\tan^2(t)}. \stopformula As one may see from relation~(\in[eqn:tangent]), $\cos(t)$ and $\sin(t)$ can be determined by $\tan(t)$\dots This is the third formula \placeformula[Pythagora] \startformula |a+b|^2 = |a|^2 + |b|^2 \stopformula Clearly equality (\in[Pythagora]) holds for $a,b \in {\Bbb R}^n$ if and only if $(a|b) =0$, where the scalar product $(\cdot|\cdot)$ on ${\Bbb R}^n$ is defined to be \startformula (a|b) := a\cdot b =\sum_{j=1}^{n}a_jb_j, \qquad |a|^2 := (a|a). \stopformula 

(Note that the above equation is {\it not\/} numbered). \stoptext