# Soddy: Finds the inner and outer Soddy circles of three given... In LearnGeom: Learning Plane Geometry

## Description

`Soddy` finds inner and outer Soddy circles of three given mutually tangent circles

## Usage

 `1` ```Soddy(A, r1, B, r2, C, r3) ```

## Arguments

 `A` Vector containing the xy-coordinates of the center of circumference 1 `r1` Radius for circumference 1 `B` Vector containing the xy-coordinates of the center of circumference 2 `r2` Radius for circumference 2 `C` Vector containing the xy-coordinates of the center of circumference 3 `r3` Radius for circumference 3

## Value

A list which contains the Soddy center and the radiuses of Soddy inner and outer circle of three mutually tangent circles

## References

http://mathworld.wolfram.com/SoddyCircles.html

## Examples

 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21``` ```x_min <- -3 x_max <- 3 y_min <- -2.5 y_max <- 3.5 CoordinatePlane(x_min, x_max, y_min, y_max) A <- c(-1,0) B <- c(1,0) C <- c(0,sqrt(3)) r1 <- 1 r2 <- 1 r3 <- 1 Draw(CreateArcAngles(A, r1, 0, 360), "black") Draw(CreateArcAngles(B, r2, 0, 360), "black") Draw(CreateArcAngles(C, r3, 0, 360), "black") result <- Soddy(A, r1, B, r2, C, r3) soddy_point <- result[[1]] inner_radius <- result[[2]] outer_radius <- result[[3]] Draw(soddy_point,"red") Draw(CreateArcAngles(soddy_point,inner_radius,0,360),"red") Draw(CreateArcAngles(soddy_point,outer_radius,0,360),"red") ```

### Example output

```NULL
NULL
NULL
NULL
NULL
NULL
NULL
```

LearnGeom documentation built on July 14, 2020, 5:06 p.m.