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6. The coordinates of point A are given. The midpoint of AB is (3,-5). Find the coordinates of point B.

a. A(4,-8)
b. A(2.5, -6.5)

User Gaby
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1 Answer

13 votes
13 votes
To find the coordinates of point B, we can use the midpoint formula. The midpoint formula is given by:

Midpoint = (x1 + x2)/2, (y1 + y2)/2

In this case, we are given that the midpoint of AB is (3,-5). We can substitute this into the midpoint formula to find the coordinates of point B.

Midpoint = (x1 + x2)/2, (y1 + y2)/2
= (3 - x1)/2, (-5 - y1)/2

We can then solve for x1 and y1, which are the coordinates of point A.

x1 = 23 - x2
y1 = 2(-5) - y2

Substituting the given coordinates of the midpoint into these equations, we get:

x1 = 6 - x2
y1 = -10 - y2

We are given that the coordinates of point A are (4,-8). Substituting these values into the equations above, we can solve for x2 and y2, which are the coordinates of point B:

x1 = 6 - x2
4 = 6 - x2
x2 = 2

y1 = -10 - y2
-8 = -10 - y2
y2 = -6

Therefore, the coordinates of point B are (2,-6). This means that the correct answer is option (a), A(4,-8).
User Kien Truong
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3.1k points