a) intersectia cu OY : x=0 f(0) = 6 A(0, 6)
intersectia cu OX : f(x) = 0 3x+6 = 0 x = -2 B(- 2, 0)
A ΔAOB = AO·OB /2 = 6·2/2 = 6cm² AB² = AO² + OB² = 36 +4 = 40 AB = 2√10
P = 6 + 2 + 2√10 = (8+√10)cm
b) AB∧OY x=0 f(0) = - 8 A(0, -8)
AB∧OX f(x) = 0 2x-8 = 0 x = 4 B(4, 0)
A Δ AOB = 8·4/2 = 16cm² AB² = 64 + 16 = 80 AB = 4√5
P = 8 + 4 + 4√5 = (12+4√5)cm