Question

A triangle has vertices on a coordinate grid at R(-7, -3), S(6,-3), and

T(-7, 2). What is the length, in units, of RS?

Answer 1

Answer: 13

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Step-by-step explanation:

Points R and S have the same y coordinate (-3) so we only have to worry about the x coordinates.

On a number line, plot markers at -7, 0, and 6

• The distance from -7 to 0 is 7 units
• The distance from 0 to 6 is 6 units

This is a total of 7+6 = 13 units

In other words, to go from -7 to 6 represents 13 spaces.

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Alternative method:

Subtract the x coordinates and apply absolute value to ensure the result is never negative. Negative distance isn't possible.

|R - S| = |-7-6| = |-13| = 13

or

|S - R| = |6 - (-7)| = |6+7| = |13| = 13

Both methods only work if the y coordinates are the same, or if both x coordinates are the same. If both were different, then you would have to use the distance formula.