Answer: The length of JF = 16 units.
Step-by-step explanation:
Given: In triangle DEF, segment DJ is a perpendicular bisector of side EF.
i.e. DJ is perpendicular to EF and DJ divides EF into two equal parts EJ and JF. [The perpendicular bisector is a line that is perpendicular to a line segment and splits it into two congruent segments.]
If EJ is 3y-8 and JF is 7y-40.
Then, [tex]3y-8=7y-40[/tex]
[tex]\Rightarrow\ 7y-3y=40-8\\\\\Rightarrow\ 4y=32\\\\\Rightarrow\ y=8 \text{ [Divide both sides by 4]}[/tex]
JF= 7(8)-40 =56-40= 16 units
Hence, the length of JF = 16 units.
