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1 vote
What is the equation for the parabola that

has a focus at (-7, 6) and a directrix of x
1?

User Chronoxor
by
5.8k points

1 Answer

2 votes

Answer:

Step-by-step explanation:

Parabola's equation is

y

=

1

16

(

x

7

)

2

+

1

and vertex is

(

7

,

1

)

.

Step-by-step explanation:

Parabola is locus of a point which moves so that its distance from a given point calld focus and a given line ccalled directrix is always constant.

Let the point be

(

x

,

y

)

. Here focus is

(

7

,

5

)

and distance from focus is

(

x

7

)

2

+

(

y

5

)

2

. Its distance from directrix

y

=

3

i.e.

y

+

3

=

0

is

|

y

+

3

|

.

Hence equaion of parabola is

(

x

7

)

2

+

(

y

5

)

2

)

=

|

y

+

3

|

2

or

x

2

14

x

+

49

+

y

2

10

y

+

25

=

y

2

+

6

y

+

9

or

x

2

14

x

+

65

=

16

y

i.e.

y

=

1

16

(

x

2

14

x

+

49

49

)

+

65

16

or

y

=

1

16

(

x

7

)

2

+

65

49

16

or

y

=

1

16

(

x

7

)

2

+

1

Hence parabola's equation is

y

=

1

16

(

x

7

)

2

+

1

and vertex is

(

7

,

1

)

.

graph{(1/16(x-7)^2+1-y)((x-7)^2+(y-1)^2-0.15)((x-7)^2+(y-5)^2-0.15)(y+3)=0 [-12.08, 27.92, -7.36, 12.64]}

User Robin Vinzenz
by
6.6k points