geophys (version 1.4-1)

NinePointCircle: Nine Point Circle

Description

Nine Point cirlce of a triangle

Usage

NinePointCircle(P1, P2 = c(0, 1), P3 = c(1, 0), add = FALSE, SHOW = TRUE)

Arguments

P1

vector, Point 1

P2

vector, Point 1

P3

vector, Point 1

add

add to existing plot

SHOW

create a new plot and add

Value

list of essential points:

A

2-vector, vertex point 1

B

2-vector, vertex point 2

C

2-vector, vertex point 3

D

2-vector, mid-point opposite A

E

2-vector, mid-point opposite B

F

2-vector, mid-point opposite C

G

2-vector, foot altitude point opposite A

H

2-vector, foot altitude point opposite B

I

2-vector, foot altitude point opposite C

J

2-vector, mid point from S-A

K

2-vector, mid point from S-B

L

2-vector, mid point from S-C

S

2-vector, Intersection point of altitudes

CEN

2-vector, center of nine point circle

R

radius of nine point circle

Details

circle passes through nine points that can be calculated for any triangle. Also known as Feuerbach's circle, Euler's circle, Terquem's circle, the six-point circle, the twelve-point circle, the n-point circle, the medioscribed circle, the mid circle, the circum-midcircle.

References

<http://en.wikipedia.org/wiki/Nine-point_circle>

See Also

TriangleInfo, TriangleCenter

Examples

# NOT RUN {
  P1 = 10*runif(2)
      P2 =  10*runif(2)
      P3 =  10*runif(2)

      TRI =  NinePointCircle(P1, P2, P3, add=TRUE, SHOW=TRUE)



# }