Question

A cone has a diameter of 9 inches and a height of 12 inches. Find the volume of the cone to the nearest tenth.


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Find the area of a circle with d = 19 km. Use 3.14 for ππ. Round to the nearest tenth.

Area is the number of cubic units needed to fill a space. True or False

Answer 1

1)
The formula for calculating the cone volume is: 
$V = \frac{ \pi *r^2*h}{3}$

Data:
V (volume) = ?
h (height) → h = 12 in
d (diagonal) = 9 in , if: d = 2*r , soon: 9 = 2*r → 2r = 9 → r = 9/2 → r = 4.5 in
Use: $\pi \approx 3.14$

Solving:
$V = \frac{ \pi *r^2*h}{3}$
$V = \frac{ 3.14 *4.5^2*12}{3}$
$V = \frac{ 3.14 *20.25*12}{3}$
$V = \frac{763.02}{3}$
$\boxed{\boxed{V = 254.34\:in^3}}\end{array}}\qquad\quad\checkmark$

2)
The circle area formula is: $A = \pi * r^2$

Data:
A (area) = ?
d (diagonal) = 19 Km , if: d = 2*r , soon: 19 = 2*r → 2r = 19 → r = 19/2 → r = 9.5 Km
Use: $\pi \approx 3.14$

Solving:
$A = \pi * r^2$
$A = 3.14*9.5^2$
$A = 3.14*90.25$
$\boxed{\boxed{A = 283.385\:Km^2}}\end{array}}\qquad\quad\checkmark$


3) False, because it's the volume, the number of cubic units needed to fill a space.