A, B and C are collinear and B is between a and C. The ratio of AB to AC is 3:2. If A is at (4,8) and B is at (7,2) what are the coordinates of point C

Respuesta :

Answer:

The coordinates of point C are (9 , -2)

Step-by-step explanation:

* Lets explain how to solve the problem

- If point (x , y) divides a line segment whose end points are

 [tex](x_{1},y_{1})[/tex] and [tex](x_{2},y_{2})[/tex] at ratio [tex]m_{1}:m_{2}[/tex]

 from the first point [tex](x_{1},y_{1})[/tex], then

 [tex]x=\frac{x_{1}m_{2}+x_{2}m_{1}}{m_{1}+m_{2}}[/tex] and

  [tex]y=\frac{y_{1}m_{2}+y_{2}m_{1}}{m_{1}+m_{2}}[/tex]

* Lets solve the problem

- A, B and C are collinear and B is between A and C

∴ Point A is [tex](x_{1},y_{1})[/tex]

∴ Point C is [tex](x_{2},y_{2})[/tex]

∴ Point B is (x , y)

- The ratio of AB to BC is 3 : 2

∴ [tex]m_{1}:m_{2}[/tex] = 3 : 2

* Lets use the rule above to find the coordinates of point C

∵ A = (4 , 8) and B = (7 , 2)

∵ [tex]m_{1}:m_{2}[/tex] = 3 : 2

∴  [tex]7=\frac{(4)(2)+x_{2}(3)}{5}[/tex]

- Multiply each side by 5

∴  [tex]35=8+3x_{2}[/tex]

- Subtract 8 from both sides

∴ [tex]27=3x_{2}[/tex]

- Divide both sides by 3

∴ [tex]9=x_{2}[/tex]

The x-coordinate of point C is 9

∴  [tex]2=\frac{(8)(2)+y_{2}(3)}{5}[/tex]

- Multiply each side by 5

∴  [tex]10=16+3y_{2}[/tex]

- Subtract 16 from both sides

∴ [tex]-6=3y_{2}[/tex]

- Divide both sides by 3

∴ [tex]-2=y_{2}[/tex]

The y-coordinate of point C is -2

* The coordinates of point C are (9 , -2)