1/23 Roznica długosci promienia okregu opisanego na kwadracie i promienia okregu wpisanego w kwadrat wynosi 2cm. Oblicz pole tego kwadratu.
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r (mniejszy okrąg) = x
R (większy okrąg) = x + 2cm
1/2a = r | * 2
2r = a
r = x = a/2
a√2/2 = R | * 2
a√2 = 2R | : √2
a = 2R / √2 * √2/√2
a = R√2
r + 2cm = R
a/2 + 2cm = a√2 / 2 | * 2
a + 4cm = a√2 | - a
4cm = a√2 - a
4cm = a (√2 - 1) | : (√2 - 1)
4cm / (√2 - 1) = a
a = 4cm / (√2 - 1) * (√2 - 1) / (√2 - 1) = 4(√2 + 1)
P = a²
P = [ 4cm * (√2 + 1) ] ²
P = [ 4 (√2 +1) ] ² = 16 ( 2 + 2√2 + 1) = 16 (3 + 2√2 ) cm²
Pozdrawiam! ; D