On a coordinate grid, JK has endpoint J at (15, −2), the midpoint of is M (1, −7). What is the length of JK?

1 Answer
Apr 25, 2015

Step 1: Determine the coordinates of the endpoint K
Step 2: Use Pythagorean Theorem to determine the length |JK|

Step 1
If M is the mid point of JK then the changes in x and y are the same from J to M and from M to K
Delta x(J:M) = 1-15 = -14
Delta y(J:M) = -7-(-2) = -5

The coordinates of K are
M+(-14,-5) = (1,-7)+(-14,-5) = (-13,-12)

Step 2:
| JK | = sqrt((Delta x(J:K))^ + (Delta y(J:K))^2)
based on the Pythagorean Theorem

|JK| = sqrt( (-13-15)^2 + (-12-(-2))^2)

=sqrt(884)

=2sqrt(441)