Find the equation of median from the vertex A of triangle ABC if A(1,2), B(2,3), C(2,-5).

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justaguide's profile pic

justaguide | College Teacher | (Level 2) Distinguished Educator

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We have to find the median from the vertex A of the triangle ABC.

Now, the mid point between B and C can be derived using the relation for the finding the mid point between two points. It states that the mid point between ( x1, y1) and (x2 , y2) is given by ( ( x1 + x2)/2, ( y1+ y2)/2).

The mid point between B(2,3) and C(2, -5) is (( 2+2)/2 , ( 3 - 5)/2)

=> ( 2 , -1)

The equation of the line joining A(1,2) and ( 2 , -1) is y+1=[(2+1)/(1-2)]*(x - 2)

=> y + 1 = -3*(x - 2)

=> y + 1 = -3x + 6

=> 3x + y - 5 = 0

The required equation of the median is 3x + y - 5 = 0

giorgiana1976's profile pic

giorgiana1976 | College Teacher | (Level 3) Valedictorian

Posted on

The median is joining the vertex and the middle of the opposite side. If the median starts from the vertex A, then, we'll have to determine the midpoint of the opposite side BC.

xM = (xB + xC)/2

xM = (2+2)/2

xM = 2

yM = (yB + yC)/2

yM = (3 - 5)/2

yM = -1

The coordinates of the midpoint M are: M(2 , -1).

Now, we'll write the equation of the median that passes through the points A and M.

(xM - xA)/(x - xA) = (yM - yA)/(y - yA)

(2 - 1)/(x - 1) = (-1- 2)/(y - 2)

1/(x - 1) = -3/(y - 2)

-3(x - 1) = y - 2

We'll remove the bracktes:

-3x + 3 + 2 = y

We'll use symmetric property and we'll combine like terms:

y = -3x + 5

The equation of the requested median is: 3x + y - 5 = 0.

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