5 B x b a y A C C 20 Дано: a:b: c = 4:3: 5.

Дано:

$$ a:b:c = 4:3:5 $$ $$ A_1B_1 = x, B_1C_1 = y, A_1C_1 = 20 $$

Пусть a = 4k, b = 3k, c = 5k. Тогда:

$$ A_1C_1 = 5k = 20 $$ $$ k = \frac{20}{5} = 4 $$

Следовательно:

$$ x = A_1B_1 = 4k = 4 \cdot 4 = 16 $$ $$ y = B_1C_1 = 3k = 3 \cdot 4 = 12 $$

Ответ: x = 16, y = 12