# cosθ-cosθ' = const. exact straight line Linkage

- Author:
- asifsound

**New type exact straight line linkage invention.**■ θ' > 180° case result is interesting. Vertical E trace line exists. ( If necessary, please mouse scroll wheel to get the smaller scaling.) cf.

**Robert's linkage**(Drag point D) ----- Robert's straight line linkage. It generates an approximate straight-line between the base. --- i.e. this famous Robert is a non-exact straight line version.

**■ Implementation sample (16 bars)**D and D'' are line-symmetric by bisector. ---- ① and O and D' are line-symmetric by the same ①'s bisector ----- ② So, we can make a linkage system to mapping from AD to A'O easily. cf. cosθ-cosθ' = const. Bisector exact straight line Sample (11 bars) cf. cosθ-cosθ' = const. Bisector exact straight line #2