bantu yg jago mtk no 8,9 sma 10 pake cara yaa

8) pada Δ ABC, besar sudut diket: x°, (2x - 1)° dan (3x - 5)°
    x + (2x - 1) + (3x - 5) = 180
    x + 2x - 1 + 3x - 5 = 180
    6x - 6 = 180
    6x = 186
      x = 31

    ∠ D = (3x - 5)° = 3(31) - 5 = 88°
    ∠ E = x = 31°
    ∠ F = (2x - 1)° = 2(31) - 1 = 61°

9) ∠ D = ∠ S
    2a + 10 = 70
    2a = 60
      a = 30°

    ∠ A = a° = 30°
    ∠ C = (a + 14)° = 30 + 14 = 44°
    ∠ D = (2a + 10)° = 2(30) + 10 = 60 + 10 = 70°
    ∠ B = 360 - ∠ A - ∠ C - ∠ D
           = 360 - 30 - 44 - 70
           = 216°

    ∠ P = ∠ A = 30°
    ∠ Q = ∠ B = 216°   
    ∠ R = ∠ C = 44°

10) Kell trapesium EFGH = 6 dm = Kell trapesium ABCD

      AB + BC + CD + DA = 6
      (3x + 2) + x + (x + 2) + (2x - 1) = 6
      7x + 3 = 6
      7x = 3
      x = 3/7

      AB = 3x + 2 = 3(3/7) + 2 = 9/7 + 2 = 23/7 = EF

      BC = 3/7 = FG

      CD = x + 2 = 3/7 + 2 = 17/7 = GH
 
      DA = 2x - 1 = 2(3/7) - 1 = 6/7 - 1 = -1/7 = EH

untuk no. 10, coba konfirmasikan lagi ke guru, karena dari persamaan, diperoleh panjang EH = negatif

semoga jelas dan membantu ya