4)
|
a2+b2=0.52 |
1) |
|
|
ra+b=6 |
2) |
|
|
a+rb=8 |
3) |
Rearrange 2) to get b=6-ra and substitute this into 3) to get
|
|
4) |
Rearrange 3) to get a=8-rb and substitute this into 2) to get
|
|
5) |
Substitute 4) and 5) into 1) to get
|
r4-402r2+768r-399=0 |
6) |
This can be solved numerically using the Newton-Raphson method; the solution is r=19.0467. Substitute this into 4) and 5) to arrive at -
|
a=0.2938 |
ra=5.596m |
|
|
b=0.4046 |
rb=7.706m |
Þ length of plank is 9.524m by Pythagoras.
Why is the previous method wrong?
