geophys (version 1.2-1)

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

P1 = 10*runif(2)
      P2 =  10*runif(2)
      P3 =  10*runif(2)

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