The vertical line creates a right triangle. The angle formed by the adjacent side (the bottom ray of the angle) of the triangle and the opposite side (the vertical line) measures 90 degrees.
This amount is the run value in your slope equation, where slope = rise/run. If you measured 7, your equation at this point would be “slope = rise/7. "
This amount is the rise value in your slope equation. If you measured 5, you would fill in your equation so that “slope = 5/7. "
To continue the example, the equation “slope = 5/7” would yield “slope = 0. 71428571. "
To continue the example, with a slope of 0. 71428571, the angle is 35. 5 degrees.
Make sure your line is perfectly straight. If it is angled up or down, it will ruin the accuracy of your equation.
Effectively, you have created a small right angle underneath the obtuse angle you want to measure, turning the top ray of the obtuse angle into the hypotenuse of your right angle.
You’re determining the slope for the angle of the acute triangle, which you can use to calculate the degrees in the acute angle. The bottom line is the run value in the equation “slope = rise/run. "
The length of your vertical line is the rise value in the equation “slope = rise/run. " Once you know the values for both rise and run, you can calculate the slope of the acute angle.
For example, the equation “slope = 2/4” would yield “slope = 0. 5. "
To continue the example, if your slope is 0. 5, the acute angle is a 26. 565-degree angle.
To continue the example, if you have an acute angle of 26. 565 degrees, you have an obtuse angle of 153. 435 degrees (180 – 26. 565 = 153. 435).
By determining the degrees of the acute angle, you can calculate the degrees in the reflex angle. You can use the basic slope equation and the inverse tangent function on your scientific calculator to find the degrees in the acute angle.
The horizontal line becomes the adjacent side of your triangle, and the vertical line becomes the opposite side of the acute angle you want to measure.
Measure the horizontal line from the vertex to the point where it meets the vertical line. Measure the vertical line from the point where it meets the horizontal line to the point where it meets the diagonal line.
For example, if your horizontal line measured 8 and your vertical line measured 4, your equation would be “slope = 4/8. " The slope of your angle would be 0. 5.
To continue the example, if your slope is 0. 5, the acute angle would measure 26. 565 degrees.
To continue the example, if the smaller acute angle measures 26. 565 degrees, the reflex angle would measure 333. 435 degrees.
