Respuesta :
ARea of base = TA - LA = 4pi
pi r^2 = 4 pi where r is radius of base.
r^2 = 4
so r = 2 Answer
pi r^2 = 4 pi where r is radius of base.
r^2 = 4
so r = 2 Answer
Answer:
r = 2 units
Step-by-step explanation:
Total area(T.A) of the circular cone is given by:
[tex]\text{T.A} =\pi r^2+ \pi r\sqrt{r^2+h^2}[/tex]
Lateral surface area(L.A) of the circular cone:
[tex]\text{L.A} = \pi r\sqrt{r^2+h^2}[/tex]
where
r is the radius and h is the height of the circular cone.
As per the statement:
[tex]T.A = 12 \pi[/tex] and [tex]L.A = 8 \pi[/tex]
then;
[tex]T.A -L.A = \pi r^2+ \pi r\sqrt{r^2+h^2}-\pi r\sqrt{r^2+h^2}[/tex]
⇒[tex]12 \pi -8 \pi = \pi r^2[/tex]
⇒[tex]4 \pi =\pi r^2[/tex]
Divide both sides by [tex]\pi[/tex] we have;
[tex]4 =r^2[/tex]
or
[tex]r^2 = 4[/tex]
⇒[tex]r= \pm\sqrt{4} =\pm 2[/tex]
r cannot be in negative
⇒[tex]r = 2[/tex] units
Therefore, radius of the circular cone is, r = 2 units
