SOLUTION: compute the angle between the line 2y-9x-18=0 and the x-axis

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Question 1086302: compute the angle between the line 2y-9x-18=0 and the x-axis
Answer by Theo(13342) About Me  (Show Source):
You can put this solution on YOUR website!
convert the equation to slope intercept form.

start with 2y - 9x - 18 = 0

add 9x and 18 to both sides of the equation to get:

2y = 9x + 18

divide both sides of the equation by 2 to get:

y = (9/2)x + 9

the slope of the line is equal to 9/2.

the angle between the line and the horizontal axis is equal to the arc-tangent of (9/2) which is equal to 77.47119229 degrees.

the following diagram shows the relationship.

$$$

the triangle formed is triangle ABC.

the angle we want is angle A.

the length of the horizontal side of this triangle is 2.

the length of the vertical side of this triangle is 9.

tan(A) is equal to 9/2.

angle A is equal to arctan(9/2).