Let x be the length of each side of the nonagon. We then split up the nonagon into 9 congruent, isosceles triangles, each with base = x and height = 12. Then the area of each triangle is 1/2 • x • 12 = 6x, so the total area of the nonagon will be 9 • 6x = 54x.
To find x, we can use some facts from geometry and trigonometry.
• In any polygon, the sum of the measures of the exterior angles is 360°. So each of these exterior angles will measure 360°/9 = 40°.
• Exterior angles are supplementary to the interior angles. So each interior angle will measure 180° - 40° = 140°.
• Each of the 9 triangles are isosceles with base angles measuring half the interior angles of the nonagon, 140°/2 = 70°.
• Cut the triangle in half along the labeled inradius of the nonagon, which has length 12. In the resulting right triangle, we have
tan(70°) = 12 / (x/2)
and solving for x gives
tan(70°) = 24/x
x = 24/tan(70°)
x = 24 cot(70°) ≈ 8.7
Then the total area of the nonagon is
54x = 54 • 24 cot(70°) ≈ 471.7
Answer:
Step-by-step explanation:
a^2+b^2=400
a^2=400-b^2
a=sqrt(400-b^2) & -sqrt(400-b^2)
-----------------------------------------------
b^2=400-a^2
b=sqrt(400-a^2) & -sqrt(400-a^2)
Combine like terms:
n^3 + 20n^ + 10n^2
= n^3 + 30n^
Divide:
=n^3 + 30n^2/10n^2
Factor:
=n^2n + 30n^2
=n^(n + 30)
= 2^2(n + 30)/10n^2
Cancel the common factor n^2:
=n + 10/10