Question

Line segments AB and CD are

congruent. Their coordinates
are A(-11, -3), B(-2,5), C(7, 1)
and D(x, 9). Find the value of x.

Answer 1

x = 16 or -2

Explanation:

If both lines are congruent, their magnitudes are equal.

To find the magnitude of a line, the equation to use is;

D = √(x2-x1)^2 + (y2-y1)^2

So for AB, we have

D = √(-2 + 11)^2 + (5 + 3)^2

D = √81 + 64 = √145

For the second line

The distance would be;

D = √x-7)^2 + (9-1)^2

D = √(x-7)^2 + 8^2

Equate both magnitude

√145 = √(x-7)^2 + 64)

Simply remove the square roots on both sides

145 = 64 + (x - 7)^2

145 -64 = (x -7)^2

81 = (x-7)^2

Thaw the square root of both sides

x - 7 = 9

or x -7 = -9

x = 9 + 7 or x = -9 + 7

x = 16 or -2