Question

Fatima plotted one side of a heptagon on a grid. the points (-8,1) and (-8,8) are joined to form a side of the heptagon. Fatima says this side is a vertical line segment that is 9 units long. What is Fatimas error?A:The side measures 25 units, not 9 units.B:The side measures 7 units, not 9 units.C:The side measures 16 units, not 9 units.D:The side measures 8 units, not 9 units

Answer 1

Answer:

The side measures 7 units, not 9 units.

Step-by-step explanation:

Edge 2020

Answer 2

The general formula for the distance between two points is

$d(A,B) = \sqrt{(A_x-B_x)^2 + (A_y-B_y)^2}$

Anyway, if A and B have the same x or y coordinates, this formula can be simplified. For example, in this case the two points have the same x coordinate of -8, so the following part of the formula simplifies:

$(A_x-B_x)^2 = (-8-(-8))^2 = (-8+8)^2 = 0^2 = 0$

So, we're left with

$d(A,B) = \sqrt{(A_y-B_y)^2}$

but the square root of a square is the absolute value of the object being squared:

$d(A,B) = \sqrt{(A_y-B_y)^2} = |A_y-B_y|$

which is this case means $|1-8| = |-7| = 7$

which is the correct length of the side.