Citation de Benguigz
$$x_{c} ; y_{c} $$
$$x_{t} ; y_{t} $$
$$x_{g} ; y_{g} $$
$$\overrightarrow{GC} \binom{x_{c}-x_{g}}{y_{c}-y_{g}} $$
$$ \overrightarrow{GC} \binom{x_{t}-x_{g}}{y_{t}-y_{g}} $$
$$GC= \sqrt{(x_{c}-x_{g})^{2} + (y_{c}-y_{g})^{2}} $$
$$GT= \sqrt{(x_{t}-x_{g})^{2} + (y_{t}-y_{g})^{2}} $$
$$\cos (\theta ) = \frac{\overrightarrow{GC}\bullet \overrightarrow{GT}}{CG\times GT} $$
$$\overrightarrow{GC}\bullet \overrightarrow{GT} = \overrightarrow{GC}(x)\times \overrightarrow{GT}(x) + \overrightarrow{GC}(y) \times \overrightarrow{GT}(y) $$
$$\theta =\arccos \frac{\overrightarrow{GC}(x)\times \overrightarrow{GT}(x) + \overrightarrow{GC}(y) \times \overrightarrow{GT}(y) } {GC\times GT} $$
$$CT^{2} =GT^{2}+GC^{2} - 2\times GT \times \cos (\theta ) $$
$$CT = \sqrt{GT^{2}+GC^{2} - 2\times GT \times \cos (\theta )} $$
$$v_{i} = \frac{CT_{i+1}CT_{i-1}}{t_{i+1}-t_{i-1}} $$
$$\omega = v \times R $$
$$rpm = \frac{60}{2\pi } \times \omega $$

Citation de Benguigz
$$x_{c} ; y_{c} $$
$$x_{t} ; y_{t} $$
$$x_{g} ; y_{g} $$
$$\overrightarrow{GC} \binom{x_{c}-x_{g}}{y_{c}-y_{g}} $$
$$ \overrightarrow{GC} \binom{x_{t}-x_{g}}{y_{t}-y_{g}} $$
$$GC= \sqrt{(x_{c}-x_{g})^{2} + (y_{c}-y_{g})^{2}} $$
$$GT= \sqrt{(x_{t}-x_{g})^{2} + (y_{t}-y_{g})^{2}} $$
$$\cos (\theta ) = \frac{\overrightarrow{GC}\bullet \overrightarrow{GT}}{CG\times GT} $$
$$\overrightarrow{GC}\bullet \overrightarrow{GT} = \overrightarrow{GC}(x)\times \overrightarrow{GT}(x) + \overrightarrow{GC}(y) \times \overrightarrow{GT}(y) $$
$$\theta =\arccos \frac{\overrightarrow{GC}(x)\times \overrightarrow{GT}(x) + \overrightarrow{GC}(y) \times \overrightarrow{GT}(y) } {GC\times GT} $$
$$CT^{2} =GT^{2}+GC^{2} - 2\times GT \times \cos (\theta ) $$
$$CT = \sqrt{GT^{2}+GC^{2} - 2\times GT \times \cos (\theta )} $$
$$v_{i} = \frac{CT_{i+1}CT_{i-1}}{t_{i+1}-t_{i-1}} $$
$$\omega = v \times R $$
$$rpm = \frac{60}{2\pi } \times \omega $$