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1) KM = √ (MN² + KN²)
           = √ (28² + 21²)
           = √ 1225
           = 35 cm
    luas segitiga = 1/2 x alas x tinggi
                         = 1/2 x 21 x 28
                         = 294 cm²
    luas layang-layang  =  2 x luas segitiga
                                     = 2 x 294
                                    = 588 cm²
    luas layang layang  = 1/2 x KM x LN
                            588  = 1/2 x 35 x LN
                            LN    = 588 / 17,5 
                            LN   = 33,6

2) PQ = √( 25² - 15² )
           = √ (625 - 225)
           = √ 400
           = 20 cm

3) RQ = √( 20² - 12² )
           = √(400 - 144)
           = √256
           = 16 cm
     luas segitiga = 1/2 alas x tinggi
                          = 1/2 12 x 16
                          = 96 cm
    luas layang-layang = 2 x luas segitiga
                                   = 2 x 96
                                   = 192 cm
    luas layang-layang = 1/2 x OR x PQ
                           192  = 1/2 x 20 x PQ
                            PQ  = 192 / 10
                            PQ  = 19,2 cm
        

1.
KM² = KN² + MN²
KM² = 21² + 28²
KM² = 441 + 784
KM² = 1225
KM = √1225
KM = 35 cm

2 × L ∆ = L layang2
2 × 1/2 × KN × MN = 1/2 × KM × LN (coret 1/2)
2 × 21 × 28 = 35 × LN
1176 = 35 LN
LN = 1176 / 35
LN = 33,6 cm

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