Kardioida
Kardioida (Yunoncha kardia — yurak va eidos — shakl) — biror aylananing radiusi shu aylana radiusiga teng bo’lgan qo’zg’almas aylana sirti bo’ylab sirpanmay g’ildiraganda uning biror nuqtasi chizadigan egri chiziq. Kardioida episikloidalar jumlasta kiradi; Paskal chig’anog’ining xususiy holi. Kardioidaning Dekart koordinatalaridagi tenglamasi: (x2 + U2)-2ax(x2 + U2)-a2u2; qutb koordinatalaridagi tenglamasi : p=tf(l+cos<p).