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Monday, January 20, 2014

More Triangle Problems, 4

Category: Analytic Geometry, Plane Geometry

"Published in Newark, California, USA"

Determine the vertices of a triangle whose sides have the midpoints (1, 0), (2, -1), and (3, 1).

Solution:

To illustrate the problem, it is better to draw the figure as follows

Photo by Math Principles in Everyday Life

Since the midpoints of the sides of a triangles are given in the problem, then we need to use midpoint formula of two points as follows



For the line segment AB:







For the line segment BC:







For the line segment AC:


 
 
 
 
 

From the set of linear equations:
 
 
 

By elimination method, solve for the values of x1, x2, and x3.

Subtract (3) from (1), we have


Add (5) and (7), we have
 
 

Substitute the value of x1 to (1)




Substitute the value of x1 to (5)




From the set of linear equations:

  


By elimination method, solve for the values of y1, y2, and y3.  

Subtract (4) from (2), we have


Substitute (6) to (8), we have




Substitute the value of y1 to (2) 




Substitute the value of y1 to (6)  




Therefore, the vertices of a triangle are