Question

B) The number of volume of a cylinder is half of its number of the total surface area.

Answer 1

Answer:

$V=179.6cm^3$

Step-by-step explanation:

the volume of a cylinder is given by:

$V=\pi r^2h$

where r is the radius and h is the height.

and the surface area:

$SA=2\pi r^2+2\pi rh$

the first term is the area of the circles and the second term is the area of the body.

since "The number of volume of a cylinder is half of its number of the total surface area." we will have that:

$V=\frac{1}{2}SA$

substitutig the equivalent expressions on each side:

$\pi r^2 h = \frac{1}{2} (2\pi r^2+2\pi r h)$

and we simplify and solve for the height (since is the value we don't know of the cylinder):

$\pi r^2 h = \pi r^2+\pi r h\\\pi r^2h-\pi rh=\pi r^2\\h(\pi r^2-\pi r)=\pi r^2\\h=\pi r^2/(\pi r^2-\pi r)$

we substitute the value of the radius $r=7cm$, and we get:

$h=\pi (7cm)^2/(\pi (7cm)^2-\pi (7cm))\\h=153.938/(153.938-21.991)\\h=153.938/131.947\\h=1.1666cm$

thus the volume is:

$V=\pi r^2h$

$V=\pi (7cm)^2(1.1666cm)\\V=179.6cm^3$

Answer 2

Answer:

the correct answer is 179.6cm3