jawabnya pakai caranya ...

11. 5p-60 = 20
3p = 60
p = 20
2p = 40
5p-60 = 40
360 - (40+40) = 280
280/2 = 140
jadi sudut ABC = 140 (D)

12. besar sudut BAD
5p-60 = 40

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