|
You may recall from sixth grade that the angles of a triangle always add up to 180 degrees. What do the angles of a quadrilateral always add up to? degrees If you wrote 360 degrees, you are correct! A pentagon can be split into three triangles. To find sum of all the interior angles of a pentagon, you can do 3 x 180. The sum of the interior angles of a pentagon is: degrees If you wrote 540 degrees, you are correct! On your PSSA formula, you will find the general formula for the sum of interior angles of a polygon. It is: Sum of angle measures = 180 (n-2) where n equals the number of sides. So, if you are trying to find the area of a hexagon (a six sided polygon), you will do: 180( - 2) or 180 (4) to get degrees. If you said: 180(6 - 2) = 180 (4) = 720 degrees, You are correct! Use the formula (pull out your PSSA sheet if needed). What is the sum of the interior angles in an octagon? degrees If you multiplied 180 by 6 (which is 2 less than 8), and got 1080 degrees, you were right! In a REGULAR polygon, all sides are equal to each other, and all angle measures are the same. This means that if you know that the angles of a regular pentagon add up to 540 degrees, and you want to know the measure of just ONE angle, you can divide 540 by 5 to get degrees If you said 108 degrees, you are correct! What is the measure of ONE angle in a regular hexagon? degrees To solve the previous problem, you should have first used the formula S = 180 (n-2) to get that the sum of the angles in a hexagon is 720 degrees. Once you have this answer, you will divide 720 by because there are 6 angles in a hexagon. This will give you your answer of 120 degrees! How many sides does a shape have if the angles add up to 1800 degrees? sides To solve the previous problem, you can divide 1800 by 180, to get 10. This means that (n - 2) = 10. Solving for n, you find that there are 12 sides! If you got 100% on this lesson, you are ready to move on to the post-test. If not, please go back and try these problems again! |