luas layang layang ABCO

cb² = 20² - 12²
cb² = 400 - 144
cb² = 256
cb = √256
cb = 16 cm

L∆ = 12 × 16 × ½
L∆ = 96 cm²

L layang² = 96 cm² × 2
L layang² = 192 cm²

semoga membantu