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erastova [34]
3 years ago
7

Question is 15 points

Mathematics
1 answer:
mihalych1998 [28]3 years ago
4 0

This is a doozy so pay attention. First thing you have to recognize is that is a trig identity, the sum identity for cosine to be exact. That formula is

cos(\alpha +\beta )=cos\alpha cos\beta -sin\alpha sin\beta.

So that means you need to find the cosine of alpha and the sin of beta. We are given the sin of alpha being 4/5 in the first quadrant. If you set up the sin ratio which is side opposite over hypotenuse of a right triangle, you put the 4 on the side opposite the reference angle, alpha, and the hypotenuse of 5 on the terminal ray and then you have to find the missing side of the right triangle you created. Using Pythagorean's theorem, you find that the missing side, which is the adjacent side to alpha, is 3. Now you can find the cosine of alpha as well, since cosine is the side adjacent, 3, over the hypotenuse, 5. So far wwe have

sin\alpha =\frac{4}{5} and

cos\alpha =\frac{3}{5} for that first angle. Now moving on to the second angle. The cosine of beta is side adjacent, 5, over the hypotenuse, 13, and we are missing the side opposite the reference angle beta. Using Pythagorean's theorem again to find the side opposite, we have that that side measures 12. Now we can find the sine of beta using that opposite side, 12, over the hypotenuse, 13. What we have now is

cos\beta =\frac{5}{13} and

sin\beta =\frac{12}{13}. According to the identity, we have to multiply those ratios now:

(\frac{3}{5}*\frac{5}{13})-(\frac{4}{5}*\frac{12}{13}).

When you do that you get

\frac{3}{13}-\frac{48}{65}.

Of course in order to subtract those 2 fractions you need a common denominator which is 65 so

\frac{15}{65}-\frac{48}{65} which gives you a final answer of -\frac{33}{65} which is the first choice given above. There you go!

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Does anyone know how to turn these fractions into percents??? please help!!!
belka [17]
You divide the fractions to get percents
4 0
3 years ago
IS THIS CORRECT?! I HAVE A BACK SIDE TOO, IF ANYTHING IS WRONG PLS PLS LMK!!
Fudgin [204]

The only error you made is on problem 3. Everything else is correct. Nice work.

-------------------------------------------------------

Here is how to solve problem 3

Plug x = 1 into the equation and solve for y

-3x + y = 1

-3*1 + y = 1 ... replace x with 1

-3 + y = 1

y - 3 = 1

y - 3 + 3 = 1 + 3 .... add 3 to both sides

y = 4

<h3>The answer is 4</h3>

-------------------------------------------------------

Verifying the answer:

Plug (x,y) = (1,4) into the equation. Both sides should be the same number after simplifying both sides.

-3x + y = 1

-3*1 + 4 = 1 ..... replace x with 1; replace y with 4

-3 + 4 = 1

1 = 1

The answer is confirmed.

If you were to graph -3x + y = 1, which is equivalent to y = 3x+1, you'll find that the point (1,4) is on this line.

4 0
3 years ago
Please help me with this question​
netineya [11]

Answer

777

Step-by-step explanation:

jnimimimimimim000

3 0
3 years ago
Read 2 more answers
4<br> Om obtuse, scalene<br> Obright, scalene<br> Oc, right, isosceles<br> Od, right, equilateral
harina [27]

Answer:

B

Step-by-step explanation:

B. right, scalene

3 0
2 years ago
(5, 3) is the solution to the system of linear equations:<br><br> True<br> False
Mkey [24]
I believe it’s true!
5 0
3 years ago
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