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Orlov [11]
3 years ago
15

If cos(x)cos(π/7)+sin(x)sin(π/7)= - (√2)/2, then x can equal:

Mathematics
1 answer:
r-ruslan [8.4K]3 years ago
8 0

\bf \textit{Sum and Difference Identities} \\\\ sin(\alpha + \beta)=sin(\alpha)cos(\beta) + cos(\alpha)sin(\beta) \\\\ sin(\alpha - \beta)=sin(\alpha)cos(\beta)- cos(\alpha)sin(\beta) \\\\ cos(\alpha + \beta)= cos(\alpha)cos(\beta)- sin(\alpha)sin(\beta) \\\\ cos(\alpha - \beta)= cos(\alpha)cos(\beta) + sin(\alpha)sin(\beta) \\\\[-0.35em] ~\dotfill\\\\

\bf cos(x)cos\left( \cfrac{\pi }{7} \right)+sin(x)sin\left( \cfrac{\pi }{7} \right)=-\cfrac{\sqrt{2}}{2}\implies cos\left( x-\cfrac{\pi }{7} \right)=-\cfrac{\sqrt{2}}{2} \\\\\\ x-\cfrac{\pi }{7}=cos^{-1}\left( -\cfrac{\sqrt{2}}{2} \right)\implies x-\cfrac{\pi }{7}= \begin{cases} \frac{3\pi }{4}\\\\ \frac{5\pi }{4} \end{cases} \\\\[-0.35em] ~\dotfill

\bf x-\cfrac{\pi }{7}=\cfrac{3\pi }{4}\implies x=\cfrac{3\pi }{4}+\cfrac{\pi }{7}~\hfill \stackrel{n ~\in~ \mathbb{Z}}{x=\cfrac{3\pi }{4}+\cfrac{\pi }{7}~~~~+2\pi n} \\\\[-0.35em] ~\dotfill\\\\ x-\cfrac{\pi }{7}=\cfrac{5\pi }{4}\implies x=\cfrac{5\pi }{4}+\cfrac{\pi }{7}~\hfill \stackrel{n ~\in~ \mathbb{Z}}{x=\cfrac{5\pi }{4}+\cfrac{\pi }{7}~~~~+2\pi n}

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vfiekz [6]

Answer: the store needs to sell 50 bicycles each month to break even

Step-by-step explanation:

The average selling price of each bicycle is ​$145.

When we talk of break even, we are referring to the point at which the income being accrued from a business is equal to the total cost of running the business. At this point, their is no profit and there is no loss.

From the example information given,

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cost of operating the bicycle store

= ​$3500 per month

The store pays an average of ​$75 per bicycle. If the store buys x bicycles per month, then,

Total the total amount the store pays per bike = 75 × x = 75x

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The average selling price of each bicycle is ​$145. This means that the selling price for x bicycles will be

145 × x = 145x

Therefore , total income is $145x

To break even,

145x = 3500 + 75x

145x - 75x = 3500

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x = 3500 / 70 = 50

8 0
3 years ago
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Doss [256]
A negative number in this wouldn't be applicable.
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Step-by-step explanation:

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