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3 years ago

AB and DC are parallel.

Mathematics

1 answer:

bekas [8.4K]3 years ago

6 0

Answer:

583 cm²

Step-by-step explanation:

To find the area of triangle BCD, we need to know the length of segment BD. That can be found from the law of sines:

BD/sin(A) = BA/sin(D)

BD = (sin(A)/sin(D))BA = sin(70°)/sin(74°)·(39 cm) ≈ 38.1249 cm

Then the area of BCD is ...

A = 1/2(DB)(DC)sin(BDC)

Angle BDC, together with the marked angles, makes a total of 180°.

∠BDC = 180° -74° -70° = 36°

A = 1/2)(38.1249 cm)(52 cm)sin(36°) ≈ 582.64 cm² ≈ 583 cm²

_____

<em>Additional comment</em>

The angle relation we used comes from the fact that consecutive interior angles where a transversal crosses parallel lines are supplementary. That means angle DAB and ADC are supplementary. Angle ADC is the sum of angles ADB and BDC, so we have ...

∠DAB +∠ADB +∠BDC = 180°

∠BDC = 180° -∠DAB -∠ADB

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3 years ago

18 POINTS! At the AoPS office, mice vary inversely with cats, that is, mice=k/cats, for some value of k. When there are 3r-19 ca

Blizzard [7]

Answer:

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Step-by-step explanation:

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$6r-27 = \dfrac{k}{r-5}\\$Cross multiply$\\k=(6r-27)(r-5)$

Taking the values of k above, we have:

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3 years ago

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Strike441 [17]

Answer:

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7 0

3 years ago

. During a year, the probability a structure will be damaged by an earthquake (A) is 0.02, that it will be damaged by a hurrican

enyata [817]

Answer:

0.9506

Step-by-step explanation:

Pr(A) = 0.02

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Pr(both) = 0.007

So,

Pr(Not A) = 1 - Pr(A)

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= 1 - 0.03

= 0.97

Pr(Not by both) = 1 - Pr(both)

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Thus,

Pr(Not B) or Pr(Not A) = 0.97 × 0.98

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7 0

3 years ago