Area=pi times radiius^2
radius=diameter/2
diamter=5
radius=5/2=2.5
pi=3.14 aprox
area=3.14 times 2.5^2
area=3.14 times 6.25
area=19.625 ft^2

round
19.6 round up
20
the answer is 20 ft^2

5 0

3 years ago

If a snowball melts so that its surface area decreases at a rate of 9 cm2/min, find the rate (in cm/min) at which the diameter d

zhuklara [117]

Answer:

The diameter decreases at a rate of 0.143cm/min when it is of 10 cm.

Step-by-step explanation:

Surface area of an snowball:

An snowball has spherical format. The surface area of an sphere is given by:

$S = d^2\pi$

In which d is the diameter of the sphere.

In this question:

We need to differentiate S implicitly in function of time. So

$\frac{dS}{dt} = 2d\pi\frac{dd}{dt}$

Surface area decreases at a rate of 9 cm2/min

This means that $\frac{dS}{dt} = -9$

At which the diameter decreases when the diameter is 10 cm?

This is $\frac{dd}{dt}$ when $d = 10$ . So

$\frac{dS}{dt} = 2d\pi\frac{dd}{dt}$

$-9 = 2(10)\pi\frac{dd}{dt}$

$\frac{dd}{dt} = -\frac{9}{20\pi}$

$\frac{dd}{dt} = -0.143$

Area in cm², so diameter in cm.

The diameter decreases at a rate of 0.143cm/min when it is of 10 cm.

8 0

2 years ago

Use quadratic formula to find the solutions to the quadratic equation 2x^2-3x+6=0

defon

Answer:

2x² - 3x + 6 = 0

a = 2 b = -3 c = 6

delta = b² - 4ac = 9 - 4.2.6 = -39

$= > x = \frac{3 + \sqrt{39}i }{4} \: or \: x = \frac{3 - \sqrt{39} i}{4}$

8 0

2 years ago

Read 2 more answers