Question

Point B has coordinates ​(​1,2​). The​ x-coordinate of point A is -8. The distance between point A and point B is 15 units. What are the possible coordinates of point​ A?

Answer 1

Answer:

The possible coordinates of point A are $A_{1} (x,y) = (-8, 14)$ and $A_{2} (x,y) = (-8, -10)$, respectively.

Step-by-step explanation:

From Analytical Geometry, we have the Equation of the Distance of a Line Segment between two points:

$l_{AB} = \sqrt{(x_{B}-x_{A})^{2} + (y_{B}-y_{A})^{2}}$ (1)

Where:

$l_{AB}$ - Length of the line segment AB.

$x_{A}, x_{B}$ - x-coordinates of points A and B.

$y_{A}, y_{B}$ - y-coordinates of points A and B.

If we know that $l_{AB} = 15$, $x_{A} = -8$, $x_{B} = 1$ and $y_{B} = 2$, then the possible coordinates of point A is:

$\sqrt{(1+8)^{2}+(2-y_{A})^{2}} = 15$

$81 + (2-y_{A})^{2} = 225$

$(2-y_{A})^{2} = 144$

$2-y_{A} = \pm 12$

There are two possible solutions:

1) $2-y_{A} = -12$

$y_{A} = 14$

2) $2 - y_{A} = 12$

$y_{A} = -10$

The possible coordinates of point A are $A_{1} (x,y) = (-8, 14)$ and $A_{2} (x,y) = (-8, -10)$, respectively.