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lorasvet [3.4K]
3 years ago
9

After several weeks of working at the grocery store, Mark has been able to put $790 into his savings account. After he withdrawa

ls $300 for new tires, he decides to start putting 15% of his weekly earnings back into his savings account.
How many whole weeks will it take Mark to restore his savings account to at least $790?

weeks
Mathematics
1 answer:
VLD [36.1K]3 years ago
5 0

Answer: 490

Step-by-step explanation:

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This is a geometry question, i need something quickly :)
Marysya12 [62]

Answer:

hope it helps mark me brainlieast!

Step-by-step explanation:

<em>For triangle ABC with sides  a,b,c  labeled in the usual way, </em>

<em> </em>

<em>c2=a2+b2−2abcosC  </em>

<em> </em>

<em>We can easily solve for angle  C . </em>

<em> </em>

<em>2abcosC=a2+b2−c2  </em>

<em> </em>

<em>cosC=a2+b2−c22ab  </em>

<em> </em>

<em>C=arccosa2+b2−c22ab  </em>

<em> </em>

<em>That’s the formula for getting the angle of a triangle from its sides. </em>

<em> </em>

<em>The Law of Cosines has no exceptions and ambiguities, unlike many other trig formulas. Each possible value for a cosine maps uniquely to a triangle angle, and vice versa, a true bijection between cosines and triangle angles. Increasing cosines corresponds to smaller angles. </em>

<em> </em>

<em>−1≤cosC≤1  </em>

<em> </em>

<em>0∘≤C≤180∘  </em>

<em> </em>

<em>We needed to include the degenerate triangle angles,  0∘  and  180∘,  among the triangle angles to capture the full range of the cosine. Degenerate triangles aren’t triangles, but they do correspond to a valid configuration of three points, namely three collinear points. </em>

<em> </em>

<em>The Law of Cosines, together with  sin2θ+cos2θ=1 , is all we need to derive most of trigonometry.  C=90∘  gives the Pythagorean Theorem;  C=0  and  C=180∘  give the foundational but often unnamed Segment Addition Theorem, and the Law of Sines is in there as well, which I’ll leave for you to find, just a few steps from  cosC=  … above. (Hint: the Law of Cosines applies to all three angles in a triangle.) </em>

<em> </em>

<em>The Triangle Angle Sum Theorem,  A+B+C=180∘ , is a bit hard to tease out. Substituting the Law of Sines into the Law of Cosines we get the very cool </em>

<em> </em>

<em>2sinAsinBcosC=sin2A+sin2B−sin2C  </em>

<em> </em>

<em>Showing that’s the same as  A+B+C=180∘  is a challenge I’ll leave for you. </em>

<em> </em>

<em>In Rational Trigonometry instead of angle we use spreads, squared sines, and the squared form of the formula we just found is the Triple Spread Formula, </em>

<em> </em>

<em>4sin2Asin2B(1−sin2C)=(sin2A+sin2B−sin2C)2  </em>

<em> </em>

<em>true precisely when  ±A±B±C=180∘k , integer  k,  for some  k  and combination of signs. </em>

<em> </em>

<em>This is written in RT in an inverted notation, for triangle  abc  with vertices little  a,b,c  which we conflate with spreads  a,b,c,  </em>

<em> </em>

<em>(a+b−c)2=4ab(1−c)  </em>

<em> </em>

<em>Very tidy. It’s an often challenging third degree equation to find the spreads corresponding to angles that add to  180∘  or zero, but it’s a whole lot cleaner than the trip through the transcendental tunnel and back, which almost inevitably forces approximation.</em>

6 0
2 years ago
You and your friend are selling magazine subscriptions. You sell 8 fewer magazine subscriptions than your friend. Together you s
Xelga [282]

Answer:

b. you sold 17

c. your friend sold 25

Step-by-step explanation:

you=y your friend=x

y=x-8

42=x +y

42=x+(x-8)

42=x+x-8

42=2x-8

50=2x

25=x

Use x to solve for y...

y=25-8

y=17

3 0
3 years ago
X/-10 -4 = 16 what's the compute ?
grin007 [14]

Answer:

x=-200

Step-by-step explanation:

x/-10 -4 = 16

Add 4 to each side

x/-10 -4+4 = 16+4

-x/10 = 20

Multiply each side by -10

-x/10 *-10 =-10*20

x = -200

4 0
3 years ago
The difference between an observational study and a experiment is that
sukhopar [10]

Answer:

observational study, you already know the outcome and you are doing it to take notes or learn while an experiment the outcome is unknown and you are seeing the reaction

Step-by-step explanation:

Hopes this helps??

4 0
2 years ago
Read 2 more answers
Brian purchased a pizza and shared 34 of the pizza with his friends. Each friend received 1/4 of the pizza. With how many friend
Veseljchak [2.6K]

Answer:

3 friends ( unless u mean 3/4 instead of 34 then its 2 friends)

Step-by-step explanation:

8 0
3 years ago
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