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3 years ago

Find the area of a sector with a central angle of 140° and a diameter of 9.6 cm. Round to the nearest tenth.

Mathematics

1 answer:

olchik [2.2K]3 years ago

8 0

Answer:

$A=28.1\ cm^2$

Step-by-step explanation:

The area of a circular sector with a central angle θ and radius r is given by:

$\displaystyle A=\frac{1}{2}r^2 \theta$

Note: The angle must be in radians.

We need to find both the radius and the angle in radians.

Diameter = 9.6 cm

Radius r=Diameter/2=4.8 cm

Angle in radians= Angle in degrees*π / 180

θ = 140*π / 180 = 2.4435 rad

Now we calculate the area:

$\displaystyle A=\frac{1}{2}(4.8)^2 2.4435$

$\boxed{A=28.1\ cm^2}$

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3 years ago

What weight of dry substance is in 150g of a 3% substance solution? What weight of an 8% solution can we have with the same weig

Pavlova-9 [17]

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2 years ago

Suppose you have a light bulb that emits 50 watts of visible light. (Note: This is not the case for a standard 50-watt light bul

natali 33 [55]

Answer:

0.049168726 light-years

Step-by-step explanation:

The apparent brightness of a star is

$\bf B=\displaystyle\frac{L}{4\pi d^2}$

where

L = luminosity of the star (related to the Sun)

d = distance in ly (light-years)

The luminosity of Alpha Centauri A is 1.519 and its distance is 4.37 ly.

Hence the apparent brightness of Alpha Centauri A is

$\bf B=\displaystyle\frac{1.519}{4\pi (4.37)^2}=0.006329728$

According to the inverse square law for light intensity

$\bf \displaystyle\frac{I_1}{I_2}=\displaystyle\frac{d_2^2}{d_1^2}$

where

$\bf I_1=$ light intensity at distance $\bf d_1$

$\bf I_2=$ light intensity at distance $\bf d_2$

Let $\bf d_2$ be the distance we would have to place the 50-watt bulb, then replacing in the formula

$\bf \displaystyle\frac{0.006329728}{50}=\displaystyle\frac{d_2^2}{(4.37)^2}\Rightarrow\\\\\Rightarrow d_2^2=\displaystyle\frac{0.006329728*(4.37)^2}{50}\Rightarrow d_2^2=0.002417564\Rightarrow\\\\\Rightarrow d_2=\sqrt{0.002417564}=\boxed{0.049168726\;ly}$

Remark: It is worth noticing that Alpha Centauri A, though is the nearest star to the Sun, is not visible to the naked eye.

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3 years ago