Locus problem help ! (2 Viewers)

aanthnnyyy

Active Member
Joined
Feb 10, 2014
Messages
289
Gender
Male
HSC
2015
Q. Write down the equation of the locus of a point P that is 2 units from the point A(1,-3)

I assume you have to use distance formula but I'm sorta stuck :/
 

InteGrand

Well-Known Member
Joined
Dec 11, 2014
Messages
6,109
Gender
Male
HSC
N/A
Q. Write down the equation of the locus of a point P that is 2 units from the point A(1,-3)

I assume you have to use distance formula but I'm sorta stuck :/
Just a circle of radius 2 units, with A as the centre.
 

DatAtarLyfe

Booty Connoisseur
Joined
Mar 10, 2015
Messages
1,805
Gender
Female
HSC
2016
Can you post the question? Cause if it says "always 2 units from A(1,-3)" then the locus is just a circle,
And the equation would be: (x - 1)^2 + (y + 3)^2 = 4
 

aanthnnyyy

Active Member
Joined
Feb 10, 2014
Messages
289
Gender
Male
HSC
2015
Just a circle of radius 2 units, with A as the centre.
Zz damnit. I remember last time I did a locus question and realized its not always a circle so I felt unsure. Thanks anyways shoulda just stuck to my instincts
 

aanthnnyyy

Active Member
Joined
Feb 10, 2014
Messages
289
Gender
Male
HSC
2015
Can you post the question? Cause if it says "always 2 units from A(1,-3)" then the locus is just a circle,
And the equation would be: (x - 1)^2 + (y + 3)^2 = 4
that was the exact question but I guess it's a little ambiguous as it doesn't say ALWAYS, but I assume it's a circle since it's only 1 mark so ye
 

braintic

Well-Known Member
Joined
Jan 20, 2011
Messages
2,137
Gender
Undisclosed
HSC
N/A
Can you post the question? Cause if it says "always 2 units from A(1,-3)" then the locus is just a circle,
And the equation would be: (x - 1)^2 + (y + 3)^2 = 4
It doesn't have to say "always".
 

DatAtarLyfe

Booty Connoisseur
Joined
Mar 10, 2015
Messages
1,805
Gender
Female
HSC
2016
It doesn't have to say "always".
I never said it does, but with the limited information i was given i assumed it went always otherwise they would have provided another point or a line to equate the distances.
Is that what you're saying? or are you saying for circle loci they don't need to write "always"?
 

Ambility

Active Member
Joined
Dec 22, 2014
Messages
336
Gender
Male
HSC
2016
You can intuit it out, but knowing how the formal method works is also important. It uses the distance formula.

 

Users Who Are Viewing This Thread (Users: 0, Guests: 2)

Top