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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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Minchanka [31]

Answer:

<h2><em><u>See in attachment and Mark as brainleist please.</u></em></h2>

6 0
2 years ago
Sophia had 64¢ until she spent 1 quarter. How much money does Sophia have now?
aleksklad [387]

Answer:

Sophia now has 39 cents.

Step-by-step explanation:

One quarter = 25 cents

Since Sophia had 64 cents until she spent 25 cents (1 quarter).

So we subtract 25 cents from 64 cents.

\:  \:  \: 64 \: cents \\  \frac{ - 25 \: cents}{ \:  \:  \: 39 \: cents}

Therefore, Sophia now has 39 cents.

7 0
2 years ago
The bill at a restaurant came to $136.40. The patrons decided to leave a 15% tip. What was the total bill including tip?
lys-0071 [83]

Answer:

156.86

Step-by-step explanation:

136.40 + 15% is 20.46 added to 136.40 is 156.86


4 0
3 years ago
Read 2 more answers
PLEASE HELP!!! ILL GIVE BRAINLIEST, EXPLAIN YOUR ANSWER PLEASE
mart [117]

Answer: -20v^3 - 30x^2 +20

Step-by-step explanation:

simply multiply each term inside of the parentheses by -5.

4 0
3 years ago
Read 2 more answers
Alr, this is the last question im asking for today. pls help
JulsSmile [24]

you already know i gotchu :)

Answer: u = 5

Step-by-step explanation:

first, i moved the terms.

-4u + 10u = 37 - 7

then, i collected the like terms and calculated them.

6u = 30

finally, i divided both sides.

u = 5

4 0
3 years ago
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