



 
Hi Olive, If Lisa ran 3km north and then 4km east she ran a total of $3 + 4 = 7 \mbox{km,}$ but I expect that is not the question that was asked, I expect you were asked something "What is the distance between where she started and where she ended?" Draw a diagram with the point $S$ where she started, move 3 units north to a point where she turned. Label this point $T.$ Turn 90 degrees and proceed 4 units to the point $E$ where she ended. You want the distance from $S$ to $E$. In your diagram triangle $STE$ is a right triangle and you know the lengths of 2 of the sides so Pythagoras can help you find the length of the third side. Write back if you need more assistance,  


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