For instance, a triangle has 3 sides and 3 interior angles while a square has 4 sides and 4 interior angles.
The angles in a triangle (a 3-sided polygon) total 180 degrees. The angles in a quadrilateral (a 4-sided polygon) total 360 degrees. The angles in a pentagon (a 5-sided polygon) total 540 degrees. The angles in a hexagon (a 6-sided polygon) total 720 degrees. The angles in an octagon (an 8-sided polygon) total 1080 degrees.
Equilateral triangles and squares are examples of regular polygons, while the Pentagon in Washington, D. C. is an example of a regular pentagon and a stop sign is an example of a regular octagon.
For example, if you know that 4 of the angles in a pentagon measure 80, 100, 120, and 140 degrees, add the numbers together to get a sum of 440. Then, subtract this sum from the total angle measure for a pentagon, which is 540 degrees: 540 – 440 = 100 degrees. So, the missing angle is 100 degrees.
If you have a graphing calculator, simply type 0. 5 and press sine-1. If you don’t have a graphing calculator, use an online chart to find the value. Both will show that x = 30 degrees.
Plug 0. 833 into your graphing calculator and press cosine-1. Alternatively, look up the value in a cosine chart. The answer is 33. 6 degrees.
Find the value in a tangent chart or press 0. 75 on your graphing calculator, then tangent-1. This is equal to 36. 9 degrees.
