Find the angle made by line 18x-3y-21=0 with x axis?

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justaguide | College Teacher | (Level 2) Distinguished Educator

Posted on

We have the equation of the line 18x-3y-21=0.

18x - 3y - 21 = 0

=> -3y = 21 - 18x

=> 3y = -21 + 18x

=> y = -7 + 6x

Now y = 6x - 2 is in the form where the slope is 6 and the y-intercept is -7.

The slope of the line is the tangent of the angle it makes with the x-axis.

So if the angle made is A, tan A = 6

A = arc tan 6.

A = 80.53 degrees.

Therefore the line makes an angle 80.53 degrees with the x- axis.

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neela | High School Teacher | (Level 3) Valedictorian

Posted on

The given equation of the line is 18x-3y-21=0. We rewrite the equation in slope intercept form,:18x- 21 = 3y. Or 3y = 18x-21. Dividing the equation by 3, we get:

y  = 6x - 7

Therefore the slope of the line with x axis is 6.

So the angle the line 18x-3y-21=0 makes with x axis is  is arc tan 6 = 80.54 degree .

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