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Sliva [168]
3 years ago
7

Cos 130 cos 40 + sin 130 sin 40

Mathematics
1 answer:
Liula [17]3 years ago
5 0
Cos(a)cos(b) + sin(a)sin(b) = cos(a-b)

cos(130-40) = cos(90) = 0
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Help! <br> Which expression is equivalent? <br> On edge
Ira Lisetskai [31]

Answer: Choice B

x^{1/8}y^{8}

======================================================

Explanation:

The two rules we use are

(a*b)^c = a^c*b^c

(a^b)^c = a^{b*c}

When applying the first rule to the expression your teacher gave you, we can say that:

\left(x^{1/4}y^{16}\right)^{1/2} = \left(x^{1/4}\right)^{1/2}*\left(y^{16}\right)^{1/2}

Then applying the second rule lets us say

\left(x^{1/4}\right)^{1/2}*\left(y^{16}\right)^{1/2} = x^{1/4*1/2}*y^{16*1/2} = x^{1/8}y^{8}

Therefore,

\left(x^{1/4}y^{16}\right)^{1/2}  = x^{1/8}y^{8}

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

In short, we just multiplied each exponent inside by the outer exponent 1/2.

So that explains why the exponents go from {1/4,16} to {1/8,8} for x and y in that exact order.

7 0
3 years ago
Karl has stamps in his desk drawer. The possible combinations of stamps are shown below in the attachment.
ArbitrLikvidat [17]

The table gives the different combinations of stamps Karl has

the first option says that


a. The total number of stamps is 25.

according to this the addition of stamps for each combination should be 25

1st combination is 18 + 17 = 35

therefore this statement is wrong as the addition of stamps is 35 stamps


b. The total value of the stamps is $18.75.

lets check the first combination

18 x $ 0.45 + 17 x $ 0.65 = 8.1 + 11.05 = $19.15

so this statement too is wrong


c. The total number of stamps is 35.

as calculated above we know that the sum of the stamps in the first combination is 35

so lets check for the other combinations

20 + 15 = 35

22 + 13 = 35

25 + 10 = 35

so the answer is 35

this statement is correct


d.The total value of the stamps is $19.15

lets check the value for the third combination

22 x 0.45 + 13 x 0.65 = 9.9 + 8.45 = $18.35

this value isnt equal to $ 19.15

therefore this statement too is wrong


correct answer is C

4 0
3 years ago
Read 2 more answers
Directions: for questions 1 through 4, find the diagonal length of each solid figure.
Alex787 [66]
\text{The length of the diagonal is }11.2\text{ mm}

Here, we want to find the diagonal of the given solid

To do this, we need the appropriate triangle

Firstly, we need the diagonal of the base

To get this, we use Pythagoras' theorem for the base

The other measures are 6 mm and 8 mm

According ro Pythagoras' ; the square of the hypotenuse equals the sum of the squares of the two other sides

Let us have the diagonal as l

Mathematically;

\begin{gathered} l^2=6^2+8^2 \\ l^2\text{ = 36 + 64} \\ l^2\text{ =100} \\ l\text{ = }\sqrt[]{100} \\ l\text{ = 10 mm} \end{gathered}

Now, to get the diagonal, we use the triangle with height 5 mm and the base being the hypotenuse we calculated above

Thus, we calculate this using the Pytthagoras' theorem as follows;

\begin{gathered} d^2=5^2+10^2 \\ d^2\text{ = 25 + 100} \\ d^2\text{ = 125} \\ d\text{ = }\sqrt[]{125} \\ d\text{ = }11.2\text{ mm} \end{gathered}

7 0
1 year ago
Find the value of x for which ABCD must be a parallelogram.
densk [106]
For a parallelogram, the parallel sides must be the same length. This means you can set their lengths equal to each other. Get like terms on the same side to calculate x.

3x-5=2x+3
3x-5+5=2x+3+5
3x=2x+8
3x-2x=2x-2x+8
x=8

x=8
4 0
3 years ago
Please help this question.
sergejj [24]

Answer:

a). 59.049°C

b). 2.1179 seconds

Step-by-step explanation:

Expression representing the final temperature after decrease in temperature of the metal from 100°C to T°C is,

T = 100(0.9)^{x}

where x = duration of cooling

a). Temperature when x = 5 seconds

T = 100(0.9)⁵

  = 59.049

  ≈ 59.049°C

b). If the temperature of the metal decreases from 100°C to 80°C

Which means for T = 80°C we have to calculate the duration of cooling 'x' seconds

80 = 100(0.9)^{x}

0.8 = (0.9)^{x}

By taking log on both the sides

log(0.8) =log[(0.9)^{x}]

-0.09691 = x[log(0.9)]

-0.09691 = -0.045757x

x = \frac{0.09691}{0.045757}

x = 2.1179

x ≈ 2.1179 seconds

3 0
3 years ago
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