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Liula [17]
3 years ago
15

PLEASE HELP!!! I don’t understand

Mathematics
1 answer:
asambeis [7]3 years ago
3 0

Answer:

Step-by-step explanation:

Use the half angle identity for cosine:

cos(x/2)=+ or - sqrt(1+cos(x))/sqrt(2)

I'm going to figure out the sign part first for cos(x/2)...

so x is in third quadrant which puts x between 180 and 270

if we half x, x/2 this puts us between 90 and 135 (that's the second quadrant)

cosine is negative in the second quadrant

so we know that

cos(x/2)=-sqrt(1+cos(x))/sqrt(2)

Now we need cos(x)... since we are in the third quadrant cos(x) is negative...

If you draw a reference triangle sin(x)=3/5 you should see that cos(x)=4/5 ... but again cos(x)=-4/5 since we are in the third quadrant.

So let's plug it in:

cos(x/2)=-sqrt(1+4/5)/sqrt(2)

No one likes compound fractions (mini-fractions inside bigger fractions)

Multiply top and bottom inside the square roots by 5.

cos(x/2)=-sqrt(5+4)/sqrt(10)

cos(x/2)=-sqrt(9)/sqrt(10)

cos(x/2)=-3/sqrt(10)

Rationalize the denominator

cos(x/2)=-3sqrt(10)/10

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Carson and Jayden kept track of how many miles they ran during one week. Carson ran a total of 43 miles, which was 12 miles more
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Answer:

31

Step-by-step explanation:

So the answer is 31 because

Carson ran 43

Jayden ran 12 miles less

so subtract 43-12=31

7 0
2 years ago
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A rental car costs $65 for one day plus an additional $0.35 per mile.
vredina [299]

Answer:

$105.25

Step-by-step explanation:

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Have a great day!

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2 years ago
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What is 8,236 rounded by tenths?
rusak2 [61]

I believe the answer is 8.2

8 0
3 years ago
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the lateral area of a cone with a diameter of 15 yards is about 287.5 square yards. to the nearest tenth, what is the slant heig
irina1246 [14]
Lateral area of the cone is given by:
LA=πr√(h²+r²)
where:
h=height
r=radius
Given that LA=287.5 yd² and r=(15/2) yds, then the height will be:
287.5=7.5π√(h²+7.5²)
solving for h we get:
(287.5/7.5π)²=h²+7.5²
thus
h²=(287.5/7.5π)²-7.5²
h²=63.1851597
 To get the slant height we use Pythagorean theorem.
c²=a²+b²
a²=h², b²=7.5²
thus
c²=h²+7.5²
c²=63.1851597+56.25
c²=119.4351597
c=10.92864~10.9 yards
3 0
3 years ago
The figure below shows a rectangular prism and a cube: A rectangular prism and a cube are drawn side by side. The length of the
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6.4/0.008=800
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2 years ago
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