the standard form for a horizontal ellipse is
X^2/a^2 + y^2/b^2 = 1
Substitute 54 for b and and use (8,18) as the
point to find a
x=8
y=18
8^2/a^2 + 18^2/54^2 =1
64/a^2 + 324/2916 = 1
324/2916 reduces to 1/9
64/a^2 + 1/9 = 1
64/a^2= 1-1/9
64/a^2 = 8/9
64*9/8 = a^2
576/8 = 72
A^2 = 72
A = square root(72) = 8.485
So formula
would be x^2/72 + y^2/2916 =1
5^2(2-sqrt3) is the answer here is the link to how to do it https://socratic.org/questions/suppose-an-isosceles-triangle-abc-has-a-30-and-b-c-5-what-is-the-leng...
I hope you meant find x
5x + 3x + 2x = 180. x=18
(20 + 22 + 17) - 7 - 12 - (9 - x) = 37;
59 - 19 - 9 + x = 37;
31 + x = 37;
x = C) 6