A cone made of cardboard has a vertical height of 8 cm and a radius of 6 cm. If this cone is cut along the slanted height to make a sector, what is the central angle, in degrees, of the sector?

Respuesta :

Answer:

216 degrees is the answer.

Step-by-step explanation:

The vertical height of the cone = 8 cm  

The radius of the cone = 6 cm

The perimeter or circumference of the base of the cone is given by:

P = [tex]2\pi r[/tex]

[tex]2\pi \times6[/tex] = [tex]12\pi[/tex]

Now the slanted height is calculated using Pythagoras theorem:

H = [tex]\sqrt{r^{2}+h^{2}}[/tex]

= [tex]\sqrt{6^{2}+8^{2} }[/tex]

[tex]\sqrt{36+64}=\sqrt{100}[/tex] = 10  

Let 'θ' is the sector angle that we have to find.  

Arc length of the sector is equal to the perimeter.

Arc length = [tex]10[/tex]θ

[tex]12\pi =10[/tex]θ

θ=[tex]12\pi /10[/tex]

[tex]θ=1.2\pi[/tex] (radian)

we know that 1 pi radian = 180 degrees.

So, 1.2 pi radian = [tex]1.2\times180=216[/tex] degrees