(1)∵ can be known from the following formula: in Rt△ADE, ∠ α = 28, DE = BC = 15.2m,

∴AE = de×tanα= 15.2×tan 28≈8.04m

∴ AB = AE+EB = 1.56+8.04 ≈ 9.6m，

A: The height of the flagpole is about 9.6 meters.

(2) The average height of flagpole measured by four groups of students is (9.8+9.6+9.7+9.6) ÷ 4 ≈ 9.7m. 。