The formula for a regular polygon, which this one is, is A = 1/2 ap where a is the apothem and p is the perimeter. 20.8 * 7 = 145.6 which is the perimeter, so now just multiply by 21.6 and .5. 145.6 * 21.6 * .5 = 1572.48, or B above.
Step-by-step explanation:
I think this will help you. Thanks.
To solve for the last side of the triangle, use the Pythagorean Theorem:
(8)^2 + x^2 = (9)^2
x = sqrt of 17
However, this is a NEGATIVE sqrt 17 because the terminal side is in quadrant 4, meaning that this side is under the X-axis and therefore negative.
Now that you know the side opposite of u in the triangle, do opposite/hypotenuse.
sin u = -(sqrt 17)/9
