# TriangleInfo: Triangle Information In geophys: Geophysics, Continuum Mechanics, Gravity Modeling

## Description

Given a triangle (three non-colinear points, return info that is useful

## Usage

 `1` ```TriangleInfo(P1, P2 = c(0, 1), P3 = c(1, 0), add = FALSE) ```

## Arguments

 `P1` vector or list(x,y) of 2D point 1 `P2` vector or list(x,y) of 2D point 2 `P3` vector or list(x,y) of 2D point 3 `add` logical, if TRUE add a variety of lines to the plot

## Details

If either P1 P2 or P3 are an x,y list, they are converted to vectors.

If P2 and P3 are missing, P1 contains all the points. Input can be list of 3 x,y values, a 3 by 2 matrix .

## Value

list

 `BI` x,y location of center of inscribed circle `CIRCUM` x,y location of center of circumscribed circle `IH` x,y location of Intersection of bisectors `CEN` centroid location `r` radius of inscribed circle `R` radius of circumscribed circle `AngBis` loci of vectors bisecting each corner on opposite leg `H` lengths of altitudes `M` lengthsof medians `TEE` lengths of perpendiculars `Area` Area of triangle

## Author(s)

Jonathan M. Lees<[email protected]>

## References

<http://en.wikipedia.org/wiki/Triangle_center>

<http://en.wikipedia.org/wiki/Encyclopedia_of_Triangle_Centers>

 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19``` ```P1 = runif(2) P2 = runif(2) P3 = runif(2) theX = c(P1[1],P2[1], P3[1]) theY = c(P1[2],P2[2], P3[2]) plot(theX , theY, asp=1) points(theX , theY) text(theX , theY, labels=1:3, pos=3) lines(c(theX, theX[1]), c(theY, theY[1]) ) TriangleInfo(P1, P2, P3, add=TRUE) ##### TriangleInfo(rbind(P1, P2, P3), add=TRUE) ```