Asked by kelly
with only have the points on a triangle how would you determine the radius and center of the incircle of that triangle?
Answers
Answered by
Reiny
There are 4 centres of a triangle,
the centroid, the orthocentre, the circumcentre and the incentre.
of those four you asked for the hardest one to find, lol
By definition, the incentre is the point in a triangle which is equidistant from each of the three sides
Are you familiar with the formula for finding the distance from a given point to a given line?
The distance from (p,q) to the line Ax + By + C = 0
= |Ap +Bq + C|/√(A^2+B^2)
so find the equation of each of the 3 sides of the triangle and write them in the general form
Ax+By+C=0
then using your given point, find 3 different expressions for the distance.
They must all be equal.
form 2 equations by setting any two of the expressions equal to each other.
That will give you 2 equations containing p and q.
solve.
Good luck, this is usually a very messy problem unless it was carefully planned.
(If somebody has a better way to do this, I would appreciate letting me know)
the centroid, the orthocentre, the circumcentre and the incentre.
of those four you asked for the hardest one to find, lol
By definition, the incentre is the point in a triangle which is equidistant from each of the three sides
Are you familiar with the formula for finding the distance from a given point to a given line?
The distance from (p,q) to the line Ax + By + C = 0
= |Ap +Bq + C|/√(A^2+B^2)
so find the equation of each of the 3 sides of the triangle and write them in the general form
Ax+By+C=0
then using your given point, find 3 different expressions for the distance.
They must all be equal.
form 2 equations by setting any two of the expressions equal to each other.
That will give you 2 equations containing p and q.
solve.
Good luck, this is usually a very messy problem unless it was carefully planned.
(If somebody has a better way to do this, I would appreciate letting me know)
Answered by
kelly
The general form of the equations are (4/3)x+y=(1688/3)
(-9/40)x+y=(19577/40)
(5/12)x+y=(-3929/12)
but then when I use the incenter(p,q)and express it for distance and set the equations equal to each other i get different things when I set the first 2 equations together than I do the second 2 and the first and last. Can you tell me what I am doing wrong?
(-9/40)x+y=(19577/40)
(5/12)x+y=(-3929/12)
but then when I use the incenter(p,q)and express it for distance and set the equations equal to each other i get different things when I set the first 2 equations together than I do the second 2 and the first and last. Can you tell me what I am doing wrong?
There are no AI answers yet. The ability to request AI answers is coming soon!
Submit Your Answer
We prioritize human answers over AI answers.
If you are human, and you can answer this question, please submit your answer.