Do zalacznika - tam gdzie jest 6 - Ty masz 3 :)
i tak:
{x+y = 2* 12,5
{(3+x)² + (3+y)² = (x+y)²
{ x = 25-y
{ (3+25-y)² + 9 + 6y+y² = (25-y+y)²
{x=25-y
{ 784 - 56y +y² + 9 +6y +y² = 625
2y²-50y+168=0
Δ=2500 - 1344
Δ = 1156
√Δ = 34
y1 = (50-34)/4
y1 =4
y2 = (50+34)/4
y2 =21
x1 = 21
x2 = 4
P trojkata = 1/2 *x*y
P trojkata = 1/2 * 4 * 21
P = 42
Pozdrawiam! :)