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saveliy_v [14]
2 years ago
15

Find the exact value of cos theta​, given that sin thetaequalsStartFraction 15 Over 17 EndFraction and theta is in quadrant II.

Rationalize denominators when applicable.
Mathematics
1 answer:
vova2212 [387]2 years ago
5 0

Answer:

cos \theta = -\frac{8}{17}

Step-by-step explanation:

For this case we know that:

sin \theta = \frac{15}{17}

And we want to find the value for cos \theta, so then we can use the following basic identity:

cos^2 \theta + sin^2 \theta =1

And if we solve for cos \theta we got:

cos^2 \theta = 1- sin^2 \theta

cos \theta =\pm \sqrt{1-sin^2 \theta}

And if we replace the value given we got:

cos \theta =\pm \sqrt{1- (\frac{15}{17})^2}=\sqrt{\frac{64}{289}}=\frac{\sqrt{64}}{\sqrt{289}}=\frac{8}{17}

For our case we know that the angle is on the II quadrant, and on this quadrant we know that the sine is positive but the cosine is negative so then the correct answer for this case would be:

cos \theta = -\frac{8}{17}

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b(a + 1) + a = b*a + b + a = ab + b + a

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3 years ago
Explain why 3/4 of 16 is the same as 3 x 16 divided by 4<br> Please Help
pogonyaev

Answer:

<em>I know that 3/4 is 75%, and I also know that 3 times 16 is 48. Since I divide 48 by 4, it is the same as multiplying 4 by 3, knowing that it is 25% of 16.</em>

Step-by-step explanation:

Since 3/4 is a fraction, all fractions can be converted into decimals.

3/4 is also known as 75%, which can be simplified into 0.75 in decimal terms.

Now that you know that 3/4 can be simplified to 0.75, you now need to take that 0.75, and multiply it by 16. You can use a calculator to do this, or you could work it out on a sheet of paper.

An easy way to do this, is to know that 25%, (0.25) of 16 is 4. This is because 4 times 4 is 16. Knowing this, if you are looking for 75% of 16, (0.75) you can multiply 4 by 3, knowing that it is 75% of 16.

The answer to that is 12.

3 x 16 = 48 and if you take 48 and divide it by 4, you will get 12.

You can explain this by writing; <em>I know that 3/4 is 75%, and I also know that 3 times 16 is 48. Since I divide 48 by 4, it is the same as multiplying 4 by 3, knowing that it is 25% of 16.</em>

7 0
3 years ago
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