I think you want to prove that a rectangle is a quadrilateral. You can prove this with definitions. The definition of a quadrilateral is that it is a shape with four sides. Since a rectangle has four sides, that proves that a rectangle is a quadrilateral.
Answer:
The area of the cone is "1,695.6 cm³".
Step-by-step explanation:
The given values are:
Diameter of cone,
d = 18 cm
then,
Radius,
r = 
= 
= 
Height,
h = 20 cm
As we know,
⇒ Area of a cone = 
On substituting the given values in the above formula, we get
⇒ = 
⇒ = 
⇒ = 
⇒ = 
1, 3, and 5 because you can multiply all these numbers to get 15