$ \frac143 = \frac286 $, $ \frac72 = \frac216 $, LCM of periods $ \frac143 $ and $ \frac72 $: write as $ \frac286, \frac216 $, GCD of 28 and 21 is 7, so period is $ \frac14\gcd(14,21) \cdot \frac1\textsome factor $. Better: find least $ T $ such that $ \frac3\pi7T = 2\pi m $, $ \frac4\pi7T = 2\pi n $, so $ T = \frac14m3 = \frac7n2 \Rightarrow \frac14m3 = \frac7n2 \Rightarrow 28m = 21n \Rightarrow 4m = 3n $. Small - Nelissen Grade advocaten