bonjour
x ² + ( x + 1 )² + ( x + 2 )² = 13 874
x² + x² + 2 x + 1 + x² + 4 x + 4 = 13 874
3 x² + 6 x + 5 = 13874
3 x² + 6 x = 13874 - 5
3 x² + 6 x = 13869
3 x² + 6 x - 13869 = 0
Δ = 36 + 166428 = 166464
x 1 = ( - 6 + 408) / 6 = 402/6 = 67
67 ² + 68 ² + 69 ² = 13 874
volume pyramide = 1/3 x c² x h
1/3 x 10 x c² = 480
c² = 480 : 10/3
c² = 480 x 3/10 = 144
c = √144 = 12
aire sphère = 4 π* R²
628 = 4 *3.14 * R²
R² = 628 : 12.56
R² = 50
R = √50 = 5 √2
