Question

Which of the following is the correct equation for the distance formula for the points (x1, y1) and (x2,y2)?

A. D=sqrt (x2-x1)^2+(y2-y1)^2
B. D=sqrt (x2-y2)^2+(y1-x1)^2
C. D=sqrt -(y2-y1)^2+(x2-x1)^2
D. D=sqrt (x1-x2)^2+(y2-y1)^2

Answer 1

A. D=sqrt( (x2-x1)^2+(y2-y1)^2 )

Explanation:

The distance between two points is the root of the sum of the squares of the differences in their corresponding coordinates. The equation of choice A is the usual formulation.

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Comment on answer choices

Because the square of a number is the same as the square of its opposite, the formula in choice D is also correct.