Solution of missingVertex Question7

In this page solution of missingvertex question7 we are going to see he detailed solution of the first question.

Question 1 :

Find the missing vertex of triangle whose two vertices are (-3,-9) (-1,6) and its centroid is (-1/3 , 2 )

 (A) (1 , -2) (B) (3 , 9) (C) (1 , -5)

Question 2 :

Find the missing vertex of triangle whose two vertices are (-3,-9) (5,-8) and its centroid is (5/3 , -8/3 )

 (A) (1 , -2) (B) (3 , 9) (C) (1 , -5)

Question 3 :

Find the missing vertex of triangle whose two vertices are (4,5) (4,2) and its centroid is (2 , 3 )

 (A) (-2 , 2) (B) (3 , 6) (C) (1 , 2)

Question 4 :

Find the missing vertex of triangle whose two vertices are (3,1) (2,2) and its centroid is (7/3 , 1 )

 (A) (-2 , 1) (B) (2 , 6) (C) (2 , 0)

Question 5 :

Find the missing vertex of triangle whose two vertices are (3,1) (0,4) and its centroid is (0 , 2 )

 (A) (-2 , 0) (B) (-3 , 1) (C) (-1 , 2)

Question 6 :

Find the missing vertex of triangle whose two vertices are (1,10) (-7,2) and its centroid is (-3 , 19/3 )

 (A) (-3 , 7) (B) (3 , 1) (C) (1 , 0)

Question 7 :

Find the missing vertex of triangle whose two vertices are (-1,-3) (2,1) and its centroid is (1 , -2 )

Solution:

Centroid of a triangle = (x₁+x₂+x₃)/3, (y₁+y₂+y₃)/3

let A,B and C be the vertices of triangle ABC. Here A (-1, -3), B (2,1) and let us take the third missing vertex be (a,b).

x₁ = -1            x₂ = 2             x₃ = a

y₁ = -3            y₂ = 1             y₃ = b

(1, -2) =  [ (-1) + 2 + a ]/3 , [ (-3) + 1 + b ]/3

(1 , -2) =  [-1 + 2 + a ]/3 , [ -3 + 1 + b ]/3

(1, -2) =  [1 + a ]/3 , [-2 + b ]/3

Equating x and y coordinates

[1 + a ]/3 = 1                   [ -2 + b ]/3  = -2

1 + a = 1 x 3                      - 2 + b = -2 x 3

1 + a = 3                              -2 + b = -6

a = 3 - 1                         b = -6 + 2

a = 2                              b = -4

Therefore the third vertex is (2,-4).

Question 8 :

Find the missing vertex of triangle whose two vertices are (1,1) (2,3) and its centroid is (-1/3 , 2 )

 (A) (-1 , 2) (B) (2 , 2) (C) (-2 , 2)