tolong jawab dengan cara

t = √s² - (a:2)²
t = √20² - (24 : 2)²
t = √400 - (12²)
t = √400 - 144
t = √256
t = 16 cm

L.Δ = a × t/2
L.Δ = 24 × 16/2
L.Δ = 24 × 8
L.Δ = 192 cm² (C)