diketahui panjang RU = 42 cm. RV =9 cm. TU = 27 cm. panjang SR adalah... cm

pakai perbandingan

TU / RV = (RU-RS) / RS
27/9       = (42-RS) / RS
27 x RS = 9 x (42-RS)
27RS = 378 - 9RS
27RS + 9RS = 378
36RS         = 378
RS     =378/36
RS = 10,5 CM