Question

ma poate ajuta si pe mine cineva?
Dau 5 stele! Promit! ​

Answer 1

Răspuns:

Explicație pas cu pas:

a) A = BC·AD/2 = 8 cm · 5 cm : 2 = 20 cm²

b) A = EF·GH/2 = 8 cm · 6 cm : 2 = 24 cm²

c) A = IJ·IK/2 = 9 cm · 12 cm : 2 = 54 cm²

d) LD ⊥ MN => A = DN·LD/2

DN = MN/2 = 4 cm/2 = 2 cm

LD² = LN²-DN² = 4²-2² = 16-4 = 12 =>

LD = √12 = √(4·3) = 2√3 cm

A = 2·2√3 /2 = 2√3 cm²

e) A = PR·QP/2 = 6 cm · 6 cm : 2 = 18 cm²

f) A = ST·UV/2 = 5 cm · 2 cm :2 = 5 cm²

g) A = XZ·WY/2 = 10 cm · 3 cm :2 = 15 cm²

h) A'D' ⊥ B'C' =>

A = A'D'·B'C'/2

A'B' = A'C' => (A'B' )² +(A'C')² = (B'C')² = 8² = 64

=> (A'B')² = 64:2 = 32 => A'B' = √32 = 4√2 cm

(A'D')² = (4√2)²-4² = 32-16 = 16 => A'D' = 4 cm

A = 4 cm ·8 cm : 2 = 16 cm²