bantuin donk kak pke cara yah???

d.tripleks = (√25²-(40/2)²) x 2 = (√625-400) x 2 = √(225) x 2 = 15x2 = 30 cm

luas tripleks = 40x30/2 = 600 cm²

d.cermin = 30-1,5-1,5 = 27 cm
t.cermin = 40-2-2 = 36 cm
luas cermin = 27 x 36/2 = 486 cm²

luas tripleks tak tertutup cermin = 600 - 486 = 114 cm²