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2 years ago

PLEASE HELP! URGENT. the law of cosines is a2+b2-2abcosC=c2. Find the value of 2abccosC.

Mathematics

1 answer:

Elodia [21]2 years ago

5 0

Answer:

Step-by-step explanation:

2ab*cos(C)=a^2+b^2-c^2

2ab*cos(C)=5^2+4^2-2^2=25+12=37

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There are 32 people who voted for Petra for class president.This represents 1/2 of the people who voted. How many people voted i

pochemuha

32 is 1/2 so do 32*2=64

4 0

3 years ago

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Work out the area of the circle and leave it in cm plz

Marat540 [252]

Answer:

132.7495 cm^2

Step-by-step explanation:

area of circle=πr^2

radius=6.5

6.5^2

42.25

42.25*3.142

132.7495

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2 years ago

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ABC Bookstore sells new books, n, for $12, and used books, u, for $8. The

Helen [10]

Answer:

D.) $12n + $8u = 112 ;u = 4 + n

Step-by-step explanation:

Given that :

Cost per new books (n) = $12

Cost per used book (u) = $8

Total revenue earned = $112

store sold 4 more used books than new books

Hence,

Total revenue should be :

Revenue from new books + Revenue from used book = total revenue

Revenue from new books = $12 * n = $12n

Revenue from used books = $8 * n = $8n

$12n + $8u = 112

Number of books sold :

Number of used books sold = 4 + number of new books sold

u = 4 + n

6 0

2 years ago

CD is perpendicular to AB and passes through point C5, 12).

Aleksandr-060686 [28]

Answer:

x intercept of CD = 17

Step-by-step explanation:

We are given a line AB with its end coordinates. and Another line segment CD which is perpendicular to AB. We have the coordinates of C , and we are asked to find the x intercept of line CD.

For that we need to find the equation of CD

we have coordinates of C , and hence if we have slope of CD we can find equation of CD

Slope of CD can be determine with the help of slope of AB as CD⊥ AB

So, the slope of CD $mCD = -\frac{1}{mAB}$

Hence we start from determining slope of AB

slope is given as

$m= \frac{y_2-y_1}{x_2-x_1}$

$m= \frac{14-(-3)}{7-(-10)}=\frac{17}{17}=1$

Hence $mAB=1$

There fore $mCD=-1$

(∵ Product of Slopes of two perpendicular lines is always -1)

Now we find the equation of CD with the help of slope -1 and coordinates of C(5,12)

$m=\frac{y-y_1}{x-x_1}$

$-1=\frac{y-12}{x-5}$

$-x+5=y-12$

$y=-x+17$

Hence we have our equation , now in order to find the x intercept we keep y = 0 in it and solve for x

$0=-x+17$

$x=17$

Hence the x intercept is 17

8 0

2 years ago

Can someone help me with this? its solving systems by substitution

yKpoI14uk [10]

Answer: x = 1 and y = 2

Given:
y = -3x + 5
5x - 4y = -3

Since we are given y, let’s sub it in the second equation.

5x - 4(-3x + 5) = -3
5x + 12x - 20 = -3
17x = 17
x = 1

After finding x, we can now find y.

5(1) - 4y = -3
-4y = -8
y = 2

Checking:

y = -3x + 5
2 = -3(1) + 5
2 = 2

5x - 4y = -3
5(1) - 4(2) = -3
-3 = -3

8 0

2 years ago