x - ∞ 0 4 +∞
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f(x) = 4 -x 4 0 punctele :
A ( 0 ,4) si B( 4,0 ) care formeaza Δ AOB drept cu catetele de lungime 4 si4
AB² = 4² +4² =16+16 =32 ⇒ AB=4√2
aria = OA·OB/2 = AB ·h / 2
4· 4 = 4√2 ·h
distanta h = 4/√2 = 2√2