Hitunglah luas permukaan gabungan bangun ruang tersebut !

<p>Lp Kubus = 6×s×s&nbsp;</p><p>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; =6×12×12</p><p>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; =864cm</p><p>Lp Balok = 2×((p×l)+(l×t)+(p×t))</p><p>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; =2×((20×12)+(12×12)+(20×12))</p><p>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; =2×(240+144+240)</p><p>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; =2×624</p><p>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;=1.248cm</p><p>&nbsp;</p><p>Lp Gabungan = 864cm+1.248cm = 2.112cm</p>