SOLUTION: The angle between the lines represented by x²+3xy+2y²=0 is ?

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Question 322090: The angle between the lines represented by x²+3xy+2y²=0 is ?
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
Factor,
x%5E2%2B3xy%2By%5E2=%28x%2By%29%28x%2B2y%29
First line:
x%2By=0
y=-x
m1=-1
Second line:
x%2B2y=0
2y=-x
m2=-1%2F2
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graph%28300%2C300%2C-5%2C5%2C-5%2C5%2C-x%2C-x%2F2%29
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The slope of the line is equal to the tangent of the angle it makes with the x-axis (measure positive angle counterclockwise from positive x-axis).
Line 1: tan%28alpha%29=-1
alpha=135degrees
Line 2: tan%28beta%29=-1%2F2
beta=153.4degrees
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beta-alpha=153.4-135=18.4 degrees