#5 please, multiple response !

The surface area of a cylinder is increasing at a rate of 9 pi square meters per hour. The height of the cylinder is fixed at 3

Alekssandra [29.7K]

Answer:

$9\pi \text{ cubic meters per hour}$

Step-by-step explanation:

Since, the surface area of a cylinder,

$A= 2\pi r^2 + 2\pi rh$ ................(1)

Where,

r = radius,

h = height,

If $A= 36\pi\text{ square meters}, h = 3\text{ meters}$

$36\pi = 2\pi r^2 + 2\pi r(3)$

$18 = r^2 + 3r$

$\implies r^2 + 3r - 18=0$

$r^2 + 6r - 3r - 18 = 0$ ( by middle term splitting )

$r(r+6)-3(r+6)=0$

$(r-3)(r+6)=0$

By zero product property,

r = 3 or r = - 6 ( not possible )

Thus, radius, r = 3 meters,

Now, differentiating equation (1) with respect to t ( time ),

$\frac{dA}{dt}= 4\pi r\frac{dr}{dt} +2\pi(r\frac{dh}{dt} + h\frac{dr}{dt})$

∵ h = constant, ⇒ dh/dt = 0,

$\frac{dA}{dt} = 4\pi r \frac{dr}{dt} +2\pi h \frac{dr}{dt}$

We have, $\frac{dA}{dt}=9\pi\text{ square meters per hour}, r = h = 3\text{ meters}$

$9\pi = 4\pi (3) \frac{dr}{dt}+2\pi (3)\frac{dr}{dt}$

$9\pi = (12\pi + 6\pi )\frac{dr}{dt}$

$9\pi = 18\pi \frac{dr}{dt}$

$\implies \frac{dr}{dt} =\frac{1}{2}\text{ meter per hour}$

Now,

Volume of a cylinder,

$V=\pi r^2 h$

Differentiating w. r. t. t,

$\frac{dV}{dt}=\pi ( r^2 \frac{dh}{dt}+h(2r)\frac{dr}{dt})=\pi ((3)(6) (\frac{1}{2})) = 9\pi \text{ cubic meters per hour}$

6 0

3 years ago

ABO please help brailest I promise Help me please I beg you !

mash [69]

I'm just going to give the answers snce so many questions

1. 2
2. 2/(m^2)
3. 1/(16x^8)
4. 3x^4
steps one: the one that starts with squareing both sides (√5x-9)^2=4^2)
23. x=9
24. 0
last graph one: third one (one that starts at 2 up from the origin)

7 0

3 years ago

Read 2 more answers

A circle has a radius of 10. An arc in circle has a central angle of 72 what is the length of the arc

BARSIC [14]

Answer:

4π

Step-by-step explanation:

-A circle subtends a total angle of 360 ° from its center.

-The length of an arc is directly proportional to the angle it subtends from the circle's center.

#The arc's length can therefore be calculated as:

$C=\pi D=2\pi r\\\\\therefore C=\frac{72\textdegree}{360\textdegree}\times 2\pi \times 10\\\\=4\pi$

Hence, the length of the arc is 4π

5 0

3 years ago

Using PYTHAGORAS THEOREM answer the question A vertical pillar ab bent at c at a height of 2.4m and its upper end b touches the

Alisiya [41]

Answer:

5.4 m

Step-by-step explanation:

The Pythagorean theorem tells you the relationship between the various lengths is ...

cd² = ac² +ad²

cd² = (2.4 m)² + (1.8 m)² = 9.00 m²

cd = √(9.00 m²) = 3.0 m

Since cd = cb and ab = ac+cb, we have ...

ab = 2.4 m + 3.0 m = 5.4 m

_____

You may recognize this as a 3-4-5 right triangle with a scale factor of 0.6. We are asked for the sum of the lengths of the "4" and "5" legs, which is ...

0.6·(4+5) = 5.4

7 0

3 years ago

For 20 points and brainliest

Korvikt [17]

Answer:

376.99in³

Step-by-step explanation:

no proof but a g00gle calculator, you're just gonna have to trust me on this one

4 0

3 years ago

Read 2 more answers