<Dd> A = (25 + 10 5 4 + 5 3 4) a 2 ≈ 3.8855 a 2 . (\ displaystyle A = \ left ((\ frac (\ sqrt (25 + 10 (\ sqrt (5)))) (4)) + 5 (\ frac (\ sqrt (3)) (4)) \ right) a ^ (2) \ approx 3.8855 \, a ^ (2).) </Dd> <P> Its volume when an edge length is known can be figured out with this formula: </P> <Dl> <Dd> V = 5 + 5 24 a 3 ≈ 0.3015 a 3 . (\ displaystyle V = (\ frac (5 + (\ sqrt (5))) (24)) \, a ^ (3) \ approx 0.3015 \, a ^ (3).) </Dd> </Dl> <Dd> V = 5 + 5 24 a 3 ≈ 0.3015 a 3 . (\ displaystyle V = (\ frac (5 + (\ sqrt (5))) (24)) \, a ^ (3) \ approx 0.3015 \, a ^ (3).) </Dd>

Volume of a pyramid with a pentagon base