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3 years ago

Cos xcos y=1/2(sin(x+y)+ sin(x-y))

Mathematics

1 answer:

garri49 [273]3 years ago

7 0

Taking Rhs

1/2 [sin(x+y)+ sin (x-y)]

using sinA + sin B = 2 cos (A+B)/2 cos( A - B)/2

1/2 [ 2 Cos ( x+y+x-y)/2 . Cos (x+y-x+y)/2]

=Cos 2x/2. Cos 2y/2 = Cos x . Cos y

Hence true

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Maddie mailed y letters in january. she mailed 3 times

Digiron [165]

The expression which shows the amount of money, in dollars Maddie spent on mailing letters in March is 3.7 +0.74 y.

Given Maddie mailed y letters in January. She mailed 3 times as many letters in February. In March she mailed 10 letters more than half of what she mailed in January and February.

Expression is combination of numbers, symbols, fraction, coefficients which are not found in equal to form.

Letters mailed in January=y

Letters mailed in February=3y

Letters mailed in March=10+(y+3y)/2

=10+2y

Amount of mailing of 1 letter=$0.37.

Amount of mailing of letters in March=0.37(10+2y)

=3.7+0.37*2y

=3.7+0.74y

Hence the expression which shows the amount of letters mailed in March is 3.7+0.74 y.

Learn more about expression at brainly.com/question/723406

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8 0

1 year ago

Mathhhhhhhhhh is harddddddd

laila [671]

given,

measure of sides of the square = 12 cm

we know, diagonal

d = a√2

now,

d = 12√2

d = 16.970 

a/q we have to round the answer to the nearest centimetres

so, 

it is 17 cm

hope this answer helps you dear! take care!

4 0

2 years ago

in the equation y equals 8X y is the dependent variable and X is the independent variable what happens to the dependent variable

goblinko [34]

As the independant variable increases, the dependant variable increases at a constant rate creating a linear relationship.

4 0

3 years ago

Peter began his trip at 1 on the number line shown above. He moved 3 positive counts on day one and 8 negative counts on day two

Montano1993 [528]

Answer:

-4

Step-by-step explanation:

1 + 3 = 4

4 - 8 = -4

4 0

2 years ago

Read 2 more answers

11 identical pairs of Air Jordan cost $660.What is the cost of one pair?

Crank

Answer:

$60

Step-by-step explanation:

11 identical pairs of Air Jordan cost $660.

To find the cost of one pair, you have simply to divide the total amount paid by the total number of pairs.

Total amount paid = $660

Total number of pairs = 11

The cost of one pair $=\$660 : 11=\$60$

6 0

3 years ago