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2013-04-24T20:27:21+02:00

exercice 5

1) Aire = 1/2.x.(x+3)

2) triangle rectangle ABH: AB² = x² + 9

3) triangle rectangle ACH: AC² = 2x²

4) Aire = 2.7 = 14 cm²

   AB = V(126+9) = 5

  AC = 4V2

exercice 7.

1) AB² + BC² = AC² en effet: 1,8² + 2,4² + 9 donc le triangle est rectangle

2) Tg ACB = 1,8/2,4 = 3/4 = 0,75 => ACB = 36,8°

3) BD = 0,6 => AD = 1,8 - 0,6 = 1,2

   ED/BC = AD/AB => ED = BC.AD/AB => ED = 2,4.1,2/1,8 = 1,6 m