( Formula 26 are normal vectors at the intersection points ; their product is scalar in Formula 27 . ) ( formula 26 are normal vectors at the intersection points . Their formula 27 product is scalar . )
(Frektor 26 adalah vektor biasa di persimpangan; produk mereka skalar dalam Formula 27.) (rumus 26 adalah vektor biasa di titik persimpangan. Produk formula 27 mereka adalah skalar.)