Odpowiedź:
z.6
( x - 1)² + ( y + 2)² = 25
Mamy S = ( 1, - 2) r =[tex]\sqrt{25} = 5[/tex]
Rysujemy okrąg o środku S i promieniu r = 5.
============================================
z.7
a ) S = ( - 2 , 3 ) r = 4
( x - a)² + ( y - b )² = r²
( x + 2)² + ( y - 3)² = 16
=====================
b )
A = ( - 4, - 5) B = ( 4, 1)
S = środek AB
S = ( [tex]\frac{-4 +4}{2} , \frac{-5 + 1}{2}[/tex] ) = ( 0 , - 2)
r² = I AS I² = ( 0 - ( - 4))² + ( - 2 - (-5))² = 16 + 9 = 25
( x - 0)² + ( y + 2)² = 25 lub x² + ( y + 2)² = 25
=========================================
c) S = ( - 3 , - 1) P = ( - 1, 3)
Mamy
( x + 3)² + ( y + 1)² = r²
oraz P = ( - 1, 3) więc po wstawieniu
( - 1 + 3)² + ( 3 + 1)² = r²
r² = 4 + 16 = 20
Odp. ( x + 3)² + ( y + 1)² = 20
==========================
z.8
S = ( 1, - 4) P = ( - 2, -5 )
r² = ( - 2 - 1)² + ( - 5 - (-4))² = 9 + 1 = 10
r = [tex]\sqrt{10}[/tex]
--------------
y = a x + b P = ( - 2 , - 5)
więc
- 5 = -2 a + b ⇒ b = 2 a - 5
czyli
y = a x + 2 a - 5
lub a x - y + 2 a - 5 = 0
Odległość tej prostej od S = ( 1, - 4 ) jest równa r = [tex]\sqrt{10}[/tex]
więc I a*1 - 1*(- 4 )+ 2 a - 5 I : [tex]\sqrt{a^2 + (-1)^2}[/tex] = [tex]\sqrt{10}[/tex]
I 3 a - 1 I = [tex]\sqrt{a^2 + 1} *\sqrt{10}[/tex]
( 3 a - 1 )² = 10 a² + 10
9 a² - 6 a + 1 = 10 a² + 10
a² + 6 a + 9 = 0
( a + 3)² = 0
a = - 3
b = 2*( - 3) - 5 = - 11
Odp. y = - 3 x - 11
===================
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Verified answer
Odpowiedź:
z.6
( x - 1)² + ( y + 2)² = 25
Mamy S = ( 1, - 2) r =[tex]\sqrt{25} = 5[/tex]
Rysujemy okrąg o środku S i promieniu r = 5.
============================================
z.7
a ) S = ( - 2 , 3 ) r = 4
( x - a)² + ( y - b )² = r²
( x + 2)² + ( y - 3)² = 16
=====================
b )
A = ( - 4, - 5) B = ( 4, 1)
S = środek AB
S = ( [tex]\frac{-4 +4}{2} , \frac{-5 + 1}{2}[/tex] ) = ( 0 , - 2)
r² = I AS I² = ( 0 - ( - 4))² + ( - 2 - (-5))² = 16 + 9 = 25
( x - 0)² + ( y + 2)² = 25 lub x² + ( y + 2)² = 25
=========================================
c) S = ( - 3 , - 1) P = ( - 1, 3)
Mamy
( x + 3)² + ( y + 1)² = r²
oraz P = ( - 1, 3) więc po wstawieniu
( - 1 + 3)² + ( 3 + 1)² = r²
r² = 4 + 16 = 20
Odp. ( x + 3)² + ( y + 1)² = 20
==========================
z.8
S = ( 1, - 4) P = ( - 2, -5 )
r² = ( - 2 - 1)² + ( - 5 - (-4))² = 9 + 1 = 10
r = [tex]\sqrt{10}[/tex]
--------------
y = a x + b P = ( - 2 , - 5)
więc
- 5 = -2 a + b ⇒ b = 2 a - 5
czyli
y = a x + 2 a - 5
lub a x - y + 2 a - 5 = 0
Odległość tej prostej od S = ( 1, - 4 ) jest równa r = [tex]\sqrt{10}[/tex]
więc I a*1 - 1*(- 4 )+ 2 a - 5 I : [tex]\sqrt{a^2 + (-1)^2}[/tex] = [tex]\sqrt{10}[/tex]
I 3 a - 1 I = [tex]\sqrt{a^2 + 1} *\sqrt{10}[/tex]
( 3 a - 1 )² = 10 a² + 10
9 a² - 6 a + 1 = 10 a² + 10
a² + 6 a + 9 = 0
( a + 3)² = 0
a = - 3
b = 2*( - 3) - 5 = - 11
Odp. y = - 3 x - 11
===================
Szczegółowe wyjaśnienie: