Square EFGH is drawn on a coordinate plane. Diagonal FH is on the line [tex]y - 3 = -\frac{1}{3}(x + 9)[/tex]. What is the slope of the diagonal GE?

A. [tex]-\frac{1}{3}[/tex]
B. [tex]\frac{1}{3}[/tex]
C. [tex]-3[/tex]
D. [tex]3[/tex]



Answer :

To find the slope of diagonal GE, we can use properties of the diagonals of a square. In a square, the diagonals are perpendicular to each other and bisect each other.

1. First, identify the slope of the given diagonal, FH.

The equation of line [tex]\( FH \)[/tex] is given in point-slope form:
[tex]\[ y - 3 = -\frac{1}{3}(x + 9) \][/tex]

To convert this to slope-intercept form (y = mx + b), where [tex]\( m \)[/tex] is the slope:
[tex]\[ y - 3 = -\frac{1}{3}x - 3 \][/tex]
[tex]\[ y = -\frac{1}{3}x - 3 + 3 \][/tex]
[tex]\[ y = -\frac{1}{3}x \][/tex]

Hence, the slope of diagonal FH is [tex]\( -\frac{1}{3} \)[/tex].

2. Next, since the diagonals of a square are perpendicular to each other, the slope of the second diagonal, GE, must be the negative reciprocal of the slope of FH.

The negative reciprocal of [tex]\( -\frac{1}{3} \)[/tex] is calculated as follows:
[tex]\[ m_{FH} = -\frac{1}{3} \][/tex]
[tex]\[ m_{GE} = -\left(\frac{1}{-1/3}\right) = 3 \][/tex]

Therefore, the slope of diagonal GE is [tex]\( 3 \)[/tex].

So, the correct answer is:
[tex]\[ \boxed{3} \][/tex]