I Thomas, Greek mathematical works (London, 1939). A normal school ruler is 12 inches while a typical tape measure is 300 ft. It's a great follow up activity for any lessons or at home learning about right angles.  Steps for Angles Construction The protractor is easier to use if you always line up one of the lines of the angle along the baseline of the protractor. For example, if you know you have an obtuse angle, then you know it is going to be more than 90 degrees. What is the sum of all the angles in a triangle? The bottom line is the, For example, the equation "slope = 2/4" would yield "slope = 0.5.". Before talking about constructing angles, let us quickly recall the different types of angles in maths, especially in geometry. wikiHow is where trusted research and expert knowledge come together. Additionally, we’ll also teach you to draw or measure angles more than 180° using a regular semicircular protractor. The angle is the amount of turn between each arm. Tip: If you get confused because the angle is upside down, turn your paper and ignore the reflex angle until the last step. The angle is opened even more now. [1] I looked and looked online and in books. How to Label Angles. refl ex angle • measures more than 180° but less than 360° 330° 225° Measure the size of this part of the angle. Then, place the tip of the compass on “A” and draw an arc through the vertex line. So after 25 minutes of alone time, I came up with a method to find an angle measure with only a ruler. If one line is more horizontal, it will typically be the easiest one to line up along the baseline. This is impossible in the general case. Research source. If you really can’t stand to see another ad again, then please consider supporting our work with a contribution to wikiHow. If you get a smaller number from your protractor, you're likely looking at the wrong scale. {"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/2\/26\/Measure-an-Angle-Without-a-Protractor-Step-1.jpg\/v4-460px-Measure-an-Angle-Without-a-Protractor-Step-1.jpg","bigUrl":"\/images\/thumb\/2\/26\/Measure-an-Angle-Without-a-Protractor-Step-1.jpg\/aid6231199-v4-728px-Measure-an-Angle-Without-a-Protractor-Step-1.jpg","smallWidth":460,"smallHeight":345,"bigWidth":728,"bigHeight":546,"licensing":"