Question 613738
I'm trying to find an easy way to solve this problem. More mathematically rather than by drawing it in the graph and deduce it. 
Question: Triangle ABC is isosceles, with A at (1,1) and B at (5,1). Which of the following could not be point C?
a. (1, -3)
b. (1,5)
c. (3, -2)
d. (3,3)
e. (5, -5)
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If AB is the base and the other 2 sides are equal, point C has to be on the perpendicular bisector of AB --> its x value has to be 3.
--> c & d would make an isoceles triangle
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The length of AB is 4 units.  If it's one of the 2 equal sides another side has to be length 4.
--> a & b would fit
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e would make the side 6 units and perpendicular to AB --> not allowed.