Question 1026569:  please help me to solve the problem that is 
The base of an equilateral triangle is  x+y-2=0 and the opposite vertex is  (2,-1) then find the equations of remaining sides of an equilateral triangle. 
 Answer by stanbon(75887)      (Show Source): 
You can  put this solution on YOUR website!  please help me to solve the problem that is 
The base of an equilateral triangle is x+y-2=0 and the opposite vertex is (2,-1) then find the equations of remaining sides of an equilateral triangle.  
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Sketch the line y = -x+2 
Plot the point (2,-1) 
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Draw a line segment from (2,-1) perpendicular to the line y = -x+2 
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Find the pt of intersection or base of that altitude. 
y = mx + b 
m = 1 
-1 = 2 + b 
b = -3 
Eq:: y = x - 3 
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System:: 
y = x - 3 
y = -x+2 
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Add and solve for "y":: 
2y = -1 
y = -1/2 
Solve for "x":: 
x-3 = -x+2 
2x = 5 
x = 5/2 
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Plot the point (5/2,-1/2) 
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Find the distance from (2,-1) to (5/2,-1/2) ; I'll call it "d". 
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Sketch the equilateral triangle described in your problem 
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Note: Each of the angles of that triangle is 60 degrees. 
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sin(60) = d/(side of the equilateral triangle) 
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Solve for the side value. 
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Cheers, 
Stan H. 
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