S1 = S2 + 39
P2/P1 = 6 / 7 = к
S2 / S1 = к²
S2 / S1 =36 / 49
S2/ S2 + 39 = 36 / 39
49 × S2 = 36× (S2 + 39)
49 S2 = 36 S2 + 1404
49 S2 - 36 S2= 1404
13 S2 = 1404
S2 = 108
ответ: 108 см².
S1 = S2 + 39
P2/P1 = 6 / 7 = к
S2 / S1 = к²
S2 / S1 =36 / 49
S2/ S2 + 39 = 36 / 39
49 × S2 = 36× (S2 + 39)
49 S2 = 36 S2 + 1404
49 S2 - 36 S2= 1404
13 S2 = 1404
S2 = 108
ответ: 108 см².