{ a,b,c } d.p ( direct proportionale ) { 2,4,6 }
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a + b + c = 180
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a / 2 = b / 4 = c / 6 = K
a / 2 = K => a = 2 K
b / 4 = K => b = 4 K
c / 6 = K => c = 6 K
2 K + 4 K + 6 K = 180
6 K + 6 K = 180
12 K = 180
K = 180 : 12
K = 15
a = 15 ·2 = 30°
b = 15 · 4 = 60°
c = 15 · 6 = 90° ⇒ triunghiul ABC este dreptunghic
