diketahui panjang diagonal sisi kubus= akar 90cm.luas permukaan kubus tersebut....cm

r√2 = √90
r = √90: √2
r = √45
r= 3√5
Lp = 6r²
= 6 ( 3√5 . 3√5 )
= 6×( 9×5)
= 6×45
= 270 cm²

diagonal sisi = s√2
√90 = s√2
s = √90/√2
s = √45

Lp = 6 x s^2
= 6 x √45^2
= 270 cm2

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