Ask question

Ask question

All categories

3 years ago

13

Which equation listed below, when solved, shows how to find the radius of a circle if the diameter is 4 inches? A) 4 ÷ 2 B) 4 x

2 C) 4 + 4 D) 4 – 4

1 answer:

Otrada [13]3 years ago

3 0

the answers is A.4÷2

You might be interested in

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

Hacer una representación gráfica para nuestro caso tenemos por un punto M pasan infinitas rectas?

vladimir1956 [14]

Answer:

make a graphical representation for our case do we have infinite lines pass through a point M?

Step-by-step explanation:

If the graphs of the equations do not intersect (for example, if they are parallel), then there are no solutions that are true for both equations. If the graphs of the equations are the same, then there are an infinite number of solutions that are true for both equations.

5 0

3 years ago

Line l and line m are straight lines. What is the measure of angle y?

qwelly [4]

Answer: 190

Step-by-step explanation:

8 0

3 years ago

Solve for x - PLEASE NEED HELP, this is my 3rd time posting it.

mafiozo [28]

Answer:

$x=58$

Step-by-step explanation:

First, remember that the maximum degree of an angle totals 360°.

Since we already have 294°, this means that what is left must total $360\textdegree - 294\textdegree= 66\textdegree$ .

Therefore, this means that our two smaller angles must equal 66°. So:

$(36)+(x-28)=66$

Solve for x. Add on the left:

$x+8=66$

Subtract 8 from both sides. Therefore, the value of x is:

$x=58$

6 0

3 years ago

I think of a number add 1 then double the results help for my mate

zalisa [80]

18 what is this for exactly..?

5 0

4 years ago

Read 2 more answers