Find the centre and radius of the circle x^2+y^2-2x+y-4=0
Answers
Answered by
0
Answer:
centre
(1,-2)
Radius:3
Explanation:
The standard eqn of a circle with centre
(a,b)and radius (r) is:(x-a)
2+(y-b)2=r2
for 2x+2y-2x+4y-4=0
we need to complete the square.
2x+2y-2x+4y-4=0
2x-2x+2y+4y-4=0
(2x-2x+12)+(2y+4y+22)
-12-22-4=0
(x-1)2+(y+2)2-9=0
centre:
(1,-2)
radius:
3²=9
Answered by
1
Answer:
centre
(
1
,
−
2
)
radius
3
Explanation:
The standard eqn of a circle with centre
(
a
,
b
)
and radius
r
is:
(
x
−
a
)
2
+
(
y
−
b
)
2
=
r
2
for
x
2
+
y
2
−
2
x
+
4
y
−
4
=
0
we need to complete the square.
x
2
+
y
2
−
2
x
+
4
y
−
4
=
0
x
2
−
2
x
+
y
2
+
4
y
−
4
=
0
(
x
2
−
2
x
+
1
2
)
+
(
y
2
+
4
y
+
2
2
)
−
1
2
−
2
2
−
4
=
0
(
x
−
1
)
2
+
(
y
+
2
)
2
−
9
=
0
(
x
−
1
)
2
+
(
y
+
2
)
2
=
9
centre
(
1
,
−
2
)
radius
√
9
=
3
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