P = 2( A + B)
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1 сторона - Х
2 сторона - X - 3
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q = 15
q = V (X^2 + (X-3)^2
15 = V X^2 + (X - 3)^2
225 = X^2 +X^2 - 6X + 9
2X^2 - 6X - 216 = 0
2(X^2 - 3X - 108) = 0
D = 9 - 4*1*(-108) = 9 + 432 = 441 V D = 21
X1 = 3 + 21 \ 2 = 12
X2 = 3 - 21 \2 = - 18\2 = - 9 (не подходит)
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Одна сторона - 12 см
Вторая сторона - (12 - 3) = 9 см
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P = 2 *(12 + 9) = 2*21 = 42
ОТВЕТ: 42 см