<PRE><B>Question 1078456</B>
What is the acute angle at the point of intersection of two lines y=-0.4x+10 and y = 3x-5? 
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Graph::
{{{graph(400,400,-5,30,-10,10,-0.4x+10,3x-5)}}}
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Notice the triangle made by the lines.
base angle where y = 3x-5 crosses the x-axis = tan^-1(3) = 71.56 degrees
base angle where y = -0.4x+10 crosses the x-axis = -tan^-1(-0.4) = 21.80 degrees
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Ans: The 3rd angle of the triangle = 180-(71.56+21.80) = 86.64 degrees
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Cheers,
Stan H.
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