Answer:
Equation of Ellipse in standard form is 
Step-by-step explanation:
Given: Center of ellipse is ( 0 , 0 )
Ellipse is 8 units high.
⇒ Length of minor axis = 8
⇒ b = 
Ellipse is 18 units wide.
⇒ Length of minor axis = 18
⇒ a = 
Standard equation of ellipse whose major axis ia x-axis is given by,

where ( h , k ) is coordinates of center.
⇒ Equation of Ellipse : 

Therefore, Equation of Ellipse in standard form is 