Tolong jwb soal ini y no 1 2,3

1. L1 = (a+b)×8×[tex] \frac{1}{2} [/tex]
         = (21×8)×[tex] \frac{1}{2} [/tex]
         = 168 ×[tex] \frac{1}{2} [/tex]
         = 84
    L2 = a×t×[tex] \frac{1}{2} [/tex]
         = 12×15×[tex] \frac{1}{2} [/tex]
         = 180 ×[tex] \frac{1}{2} [/tex]
         = 90
L bangun = L1+L2
                = 84 + 90 = 174

2. L1 = p×l
         = 18 × 10 = 180
    L2 = a×t×[tex] \frac{1}{2} [/tex]
         = 18×7×[tex] \frac{1}{2} [/tex]
         = 126 × [tex] \frac{1}{2} [/tex] = 63
L daerah yang diarsir = L1 - L2 =180-63 = 117

3. K = (25×2) + (40+30×2)
       = 50 + 140 = 190