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sweet-ann [11.9K]
3 years ago
15

Evalaute the following without using a calculator: cos(13pi/6)

Mathematics
2 answers:
strojnjashka [21]3 years ago
6 0
Answer is in the attachment below. Please open it up in a new window to see it in full.

Harman [31]3 years ago
5 0
the\ cos\ function\ is\ periodic:\ \ \ the\ period=2 \pi\\\\cos(2 \pi + \alpha )=cos \alpha \\\\------------------------\\\\cos\bigg{(} \frac{\big{13 \pi }}{\big{6}}\bigg{)}=cos\bigg{(} 2 \pi +\frac{\big{ \pi }}{\big{6}}\bigg{)}=cos\bigg{(} \frac{\big{ \pi }}{\big{6}}\bigg{)}= \frac{\big{ \sqrt{3} }}{\big{2}}
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HELP please :)
ankoles [38]
X is the amount of distilled water that must be added (in milliliters)
2/(100+x)=9/(1000)
2000=900+9x
1100=9x
122.22=x
x= 122
The answer is 122 milliliters of distilled water must be added
3 0
3 years ago
I don't need you to work it out, just theorem(s) i need to reach the answer :)
VikaD [51]
Not sure why such an old question is showing up on my feed...

Anyway, let x=\tan^{-1}\dfrac43 and y=\sin^{-1}\dfrac35. Then we want to find the exact value of \cos(x-y).

Use the angle difference identity:

\cos(x-y)=\cos x\cos y+\sin x\sin y

and right away we find \sin y=\dfrac35. By the Pythagorean theorem, we also find \cos y=\dfrac45. (Actually, this could potentially be negative, but let's assume all angles are in the first quadrant for convenience.)

Meanwhile, if \tan x=\dfrac43, then (by Pythagorean theorem) \sec x=\dfrac53, so \cos x=\dfrac35. And from this, \sin x=\dfrac45.

So,

\cos\left(\tan^{-1}\dfrac43-\sin^{-1}\dfrac35\right)=\dfrac35\cdot\dfrac45+\dfrac45\cdot\dfrac35=\dfrac{24}{25}
7 0
3 years ago
What is 2/9 = 4/x+8 i dont get this fraction solving
Dmitriy789 [7]

♥️♥️♥️♥️♥️♥️♥️♥️♥️♥️♥️♥️♥️♥️

\frac{2}{9}  =  \frac{4}{x + 8}  \\

\frac{4}{x + 8}  =  \frac{2}{9}  \\

Inverse both sides

\frac{x + 8}{4}  =  \frac{9}{2}  \\

Multiply sides by 4

4 \times  \frac{x + 8}{4}  = 4 \times  \frac{9}{2}  \\

x + 8 = 2 \times 9

x + 8 = 18

Subtract sides 8

x + 8 - 8 = 18 - 8

x = 10

Done...

♥️♥️♥️♥️♥️♥️♥️♥️♥️♥️♥️♥️♥️♥️

3 0
3 years ago
Nadia buys boxes of crackers that each has the same cost c. She represents the cost of 6 boxes of cheese crackers, 5 boxes of po
snow_lady [41]
I believe the answer is b because u need to combine like terms and 6c+2c+5c is 13c.
6 0
2 years ago
Read 2 more answers
Identify this pair of angles ​
REY [17]
They are opposite exterior angles
7 0
2 years ago
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