(^ = puissance)
1. h = 5m = 500cm
V(cylindre) = π*r²*h = π*(20)²*500 = π*400*500 = 200000πcm^3 = 628318cm^3
2. Le triangle AOB est recatangle en O
Donc A(AOB) = (Longueur*largeur)/2 = (20*20)/2 = 400/2 = 200cm^3
3. A(ABCD) = 200*4 = 800cm^3
V(poutre) = 800*500 = 400000cm^3
4. Pourcentage bois = 400000/628318*100 = 64%