Circumference of entire circle = 2 * PI * 10
circumference of entire circle =
<span>
<span>
<span>
62.832 feet
81 degrees is (9/40) of a circle
62.832 * </span></span></span><span>(9/40) = </span>
<span>
<span>
<span>
14.1372
</span>
</span>
</span>
Source:
http://www.1728.org/radians.htm
A statement that follows with little or no proof required from an already proven statement. For example, it is a theorem<span> in geometry that the angles opposite two congruent sides of a triangle are also congruent. A </span>corollary<span> to that statement is that an equilateral triangle is also equiangular</span>
We are given this
write it as the difference of cubes
use the formula for the difference of cubes
Now use the formula for the difference of squares as 
