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2 years ago

The diameter of a circle is 41 ft. Find its area to the nearest whole number.

Mathematics

2 answers:

Dafna1 [17]2 years ago

8 0

Answer:A≈1320.25ft²

Step-by-step explanation:

A=1

4πd2=1

4·π·412≈1320.25431ft²

erastova [34]2 years ago

8 0

Answer:

rounded: 1320

original: 1320.25

Step-by-step explanation:

hope this helps

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1. An account is opened with a balance of $2800earning 4.25% simple interest. What will be thebalance in the account in 30 years

JulijaS [17]

Answer:

$6370

Explanation:

The simple interest formula gives us the final amount A given the principal amount P:

$A=P(1+rt)$

where r is the interest rate and t is the time interval.

Now in our case we have

P = 2800

r = 4.25/100

t = 30 years

therefore, the above formula gives

$A=2800(1+\frac{4.25}{100}\cdot30)$

which simplifies to give

$\boxed{A=\$6370}$

Hence, the account balance after 30 years will be $6370.

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1 year ago

I need help with questions #7 and #8 plz

katen-ka-za [31]

Answer:

7. A = 40.8 deg; B = 60.6 deg; C = 78.6 deg

8. A = 20.7 deg; B = 127.2 deg; C = 32.1 deg

Step-by-step explanation:

Law of Cosines

$c^2 = a^2 + b^2 - 2ab \cos C$

You know the lengths of the sides, so you know a, b, and c. You can use the law of cosines to find C, the measure of angle C.

Then you can use the law of cosines again for each of the other angles. An easier way to solve for angles A and B is, after solving for C with the law of cosines, solve for either A or B with the law of sines and solve for the last angle by the fact that the sum of the measures of the angles of a triangle is 180 deg.

We use the law of cosines to find C.

$18^2 = 12^2 + 16^2 - 2(12)(16) \cos C$

$324 = 144 + 256 - 384 \cos C$

$-384 \cos C = -76$

$\cos C = 0.2$

$C = \cos^{-1} 0.2$

$C = 78.6^\circ$

Now we use the law of sines to find angle A.

Law of Sines

$\dfrac{a}{\sin A} = \dfrac{b}{\sin B} = \dfrac{c}{\sin C}$

We know c and C. We can solve for a.

$\dfrac{a}{\sin A} = \dfrac{c}{\sin C}$

$\dfrac{12}{\sin A} = \dfrac{18}{\sin 78.6^\circ}$

Cross multiply.

$18 \sin A = 12 \sin 78.6^\circ$

$\sin A = \dfrac{12 \sin 78.6^\circ}{18}$

$\sin A = 0.6535$

$A = \sin^{-1} 0.6535$

$A = 40.8^\circ$

To find B, we use

m<A + m<B + m<C = 180

40.8 + m<B + 78.6 = 180

m<B = 60.6 deg

I'll use the law of cosines 3 times here to solve for all the angles.

Law of Cosines

$a^2 = b^2 + c^2 - 2bc \cos A$

$b^2 = a^2 + c^2 - 2ac \cos B$

$c^2 = a^2 + b^2 - 2ab \cos C$

Find angle A:

$a^2 = b^2 + c^2 - 2bc \cos A$

$8^2 = 18^2 + 12^2 - 2(18)(12) \cos A$

$64 = 468 - 432 \cos A$

$\cos A = 0.9352$

$A = 20.7^\circ$

Find angle B:

$b^2 = a^2 + c^2 - 2ac \cos B$

$18^2 = 8^2 + 12^2 - 2(8)(12) \cos B$

$324 = 208 - 192 \cos A$

$\cos B = -0.6042$

$B = 127.2^\circ$

Find angle C:

$c^2 = a^2 + b^2 - 2ab \cos C$

$12^2 = 8^2 + 18^2 - 2(8)(18) \cos B$

$144 = 388 - 288 \cos A$

$\cos C = 0.8472$

$C = 32.1^\circ$

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3 years ago

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gayaneshka [121]

I'm going to use the substitution method.

If y = - 3/2 - 7, then:

1/2x + 5 = - 3/2x - 7

Combine like terms:

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Simplify to get:

x = - 6.

Plug - 6 back in for x in either equation.

Y = 1/2( - 6) + 5 which becomes Y = - 3 + 5.

X = - 6, Y = 2

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Dafna1 [17]

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3 years ago

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kotykmax [81]

W=-9

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Divide 3 from -27

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