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White raven [17]
3 years ago
5

Annie walks 15 feet away from her house and places a mirror on the ground. She backs 4 feet away from the mirror so that she can

see the tip of the roof. Annie's eyes are 5 feet above the ground. Annie and the house are both perpendicular to the ground. The angles between the top of the house, the mirror, and the ground and between Annie's eyes, the mirror, and the ground are congruent as shown in the image below: Image depicts a mirror on the ground between a person and a house. The mirror is 4 feet away from the person and 15 feet away from the house. What is the height of the house? Show your work and explain your reasoning in complete sentences.

Mathematics
2 answers:
Firdavs [7]3 years ago
7 0

Answer:

18.75 ft

Step-by-step explanation:

The given scenario can be drawn as shown in the following attachment.

Given that,

m\angle DCE=\angle ACB and m\angle DEC=\angle ABC=90^{\circ}

Therefore, \Delta ABC\sim \Delta DEC

\Rightarrow \dfrac{AB}{DE}=\dfrac{BC}{EC}

\Rightarrow \dfrac{AB}{5}=\dfrac{15}{4}

\Rightarrow AB=\dfrac{15\times 5}{4}=18.75 ft

AB is the height of the house.

Shkiper50 [21]3 years ago
4 0

Answer:

The roof is 18.75 ft tall.

Step-by-step explanation:

You set up a proportion by taking the height of the house (x) divided by the height of her eyes (5) is equal to the distance between the mirror and the house (15) divided by the distance between her and the mirror (4).

Then you multiply each side by 5 to get x by itself which gives you 75/4 and you simplify that to get 18.75 ft.

heres what all of that looks like:

x/5 = 15/4

x = 5(15/4)

x = 75/4

x = 18.75

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Simplify the rational expression. State any restrictions on the variable.
ExtremeBDS [4]

we are given

\frac{(n^4-10n^2+24)}{(n^4-9n^2+18)}

Firstly, we will factor numerators and denominators

\frac{(n^4-10n^2+24)}{(n^4-9n^2+18)}=\frac{(n^2-6)(n^2-4)}{(n^2-3)(n^2-6)}

we can see that

n^2 -6 is factor on both numerator and denominator

so, it will get cancelled

and n^2 -6 can not be equal to 0

so, one of restriction is

n^2-6\neq 0

n\neq -+ \sqrt{6}

we can simplify it

\frac{(n^4-10n^2+24)}{(n^4-9n^2+18)}=\frac{(n^2-4)}{(n^2-3)}

we know that denominator can not be zero

n^2-3\neq 0

n\neq -+ \sqrt{3}

so, option-B.......Answer

3 0
3 years ago
Find the value of k so that 48x-ky=11 and (k+2)x+16y=-19 are perpendicular lines.
Rufina [12.5K]

Answer: k = -1 +/- √769

<u>Step-by-step explanation:</u>

48x - ky = 11

<u>-48x        </u>  <u> -48x</u>

         -ky = -48x + 11

         \frac{-ky}{-k} = \frac{-48x}{-k} + \frac{11}{-k}    

           y =\frac{48x}{k} - \frac{11}{k}

Slope: \frac{48}{k}

*************************************************************************

 (k + 2)x + 16y = -19

<u>- (k + 2)x          </u>   -<u>(k + 2)x </u>

                 16y = -(k + 2)x - 19

                  \frac{16y}{16} = -\frac{(k + 2)x}{16} - \frac{19}{16}

                  y = -\frac{(k + 2)x}{16} - \frac{19}{16}

Slope: -\frac{(k + 2)}{16}

**********************************************************************************

\frac{48}{k} and -\frac{(k + 2)}{16} are perpendicular so they have opposite signs and are reciprocals of each other.  When multiplied by its reciprocal, their product equals -1.

-\frac{(k + 2)}{16} *  \frac{k}{48} = -1

\frac{(k + 2)k}{16(48)} = 1

Cross multiply, then solve for the variable.

(k + 2)(k) = 16(48)

k² + 2k - 768 = 0

Use quadratic formula to solve:

k = -1 +/- √769



5 0
4 years ago
Listed below are the summary statistics from samples of strontium-90 in baby teeth obtained from twelve Pennsylvania residents a
qaws [65]

Answer:

9.72

Step-by-step explanation:

s1 = 10.6383 ; s2 = 5.21289

x1 = 147.583 ; x2 = 136.417

n1 = 12 ; n2 = 12

df1 = n1 - 1 = 12 - 1 = 11

df2 = n2 - 1 = 12 - 1 = 11

The test statistic :

(x1 - x2) / sqrt[(sp²/n1 + sp²/n2)]

Pooled variance = Sp² = (df1*s1² + df2*s2²) ÷ (n1 + n2 - 2)

Sp² = ((11*10.6383) + (11*5.21289)) / 22 = 7.926

Test statistic, T* :

(147.583 - 136.417) / √(7.926 * (1/12 + 1/12))

11.166 / √(7.926 * (1/6)

11.166 / √1.321

11.166 / 1.1493476

T* = 9.7150766

Test statistic = 9.72

5 0
3 years ago
Cheryl can travel 21.6 miles on one gallon of gas. how far can cheryl travel on 6.2 gallons of gas?
boyakko [2]
21.6 miles per gallon

Multiplied by 6.2 gallons 

21.6 * 6.2 = 133.92

Cheryl can travel 133.92 (or about 134) miles on 6.2 gal. of gas.

Hope that helped!
6 0
3 years ago
Un empresario contrata a 16 obreros para realizar un trabajo y a cada uno le paga 385 €. Si el empresario quiere ganar 892 €. ¿C
OverLord2011 [107]

Answer:

7052€

Step-by-step explanation:

Si el empresario quiere gana 892€, primero tiene que encontrar el valor total a pagar a los 16 obreros y sumarle a ese valor la ganancia que quiere obtener:

Valor total a pagar a los obreros: 385€*16= 6160€

Valor a cobrar por el trabajo: 6160+892= 7052€

De acuerdo con esto, si el empresario quiere ganar 892 €, debe cobrar 7052€ por el trabajo.

5 0
3 years ago
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