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2 years ago

Cos3A-sin3A/1-2sin2A= cosA + sinA. Prove the identity

Mathematics

1 answer:

Vlad1618 [11]2 years ago

3 0

Step-by-step explanation:

(cos(3A) − sin(3A)) / (1 − 2 sin(2A))

Use double angle formula:

(cos(3A) − sin(3A)) / (1 − 4 sin A cos A)

Use triple angle formulas:

(4 cos³A − 3 cos A − 3 sin A + 4 sin³A) / (1 − 4 sin A cos A)

Group and factor:

(4 (cos³A + sin³A) − 3 (cos A + sin A)) / (1 − 4 sin A cos A)

Factor the sum of cubes:

(4 (cos A + sin A) (cos²A − cos A sin A + sin²A) − 3 (cos A + sin A)) / (1 − 4 sin A cos A)

Use Pythagorean identity:

(4 (cos A + sin A) (1 − cos A sin A) − 3 (cos A + sin A)) / (1 − 4 sin A cos A)

Factor out cos A + sin A:

(cos A + sin A) (4 (1 − cos A sin A) − 3) / (1 − 4 sin A cos A)

Simplify:

(cos A + sin A) (4 − 4 cos A sin A − 3) / (1 − 4 sin A cos A)

(cos A + sin A) (1 − 4 cos A sin A) / (1 − 4 sin A cos A)

cos A + sin A

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2 years ago

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Step-by-step explanation:

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2 years ago

The width of a rectangle is the length minus 2 units. The area of the rectangle is 35 units. What is the width, in units, of the

Andrews [41]

Answer: width = 5 units

Step-by-step explanation:

Let L represent the length of the rectangle.

The width of a rectangle is the length minus 2 units. It means that the width of the rectangle is (L - 2) units.

The formula for determining the area of a rectangle is expressed as

Area = length × width

The area of the rectangle is 35 units. It means that

L(L - 2) = 35

L² - 2L = 35

L² - 2L - 35 = 0

L² + 5L - 7L - 35 = 0

L(L + 5) - 7(L + 5) = 0

L - 7 = 0 or L + 5 = 0

L = 7 or L = - 5

Since the length cannot be negative, then

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6 0

2 years ago

You and your neighbor attempt to use your cordless phones at the same time. Your phones independently select one of ten channels

ExtremeBDS [4]

Answer:

1/100.

Step-by-step explanation:

So, we can make the following deductions from the information given in the question or problem above.

[1]. "You and your neighbor attempt to use your cordless phones at the same time."

DEDUCTION: Two people are involved, that is you and your neighbor are both involved.

[2]. "Your phones independently select one of ten channels at random to connect to the base unit. "

DEDUCTION: Both cordless phones can choose one channels each which is random. The number of channels available is ten.

Therefore, the probability that both your phone and your neighbor phone pick the same channel can be calculated or determined as follows:

The probability that both your phone and your neighbor phone pick the same channel = probability that both your phone will pick one channel out of the ten channels × the probability that your neighbor phone pick one channel out of the ten channels.

The probability that both your phone and your neighbor phone pick the same channel = 1/10 × 1/10 = 1/100.

Therefore, The probability that both your phone and your neighbor phone pick the same channel = 1/100.

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2 years ago

A cubic box is completely filled with 2,179 g of water. What is the length of one side of the box, in meters? m Explain your rea

lisov135 [29]

Answer:

$l\approx 1.296\,cm$

Step-by-step explanation:

The water density is approximately 1 gram per cubic centimeter, which means that 1 gram of water occupies a volume of a cubic centimeter. Hence, 2.179 grams occupies a volume of 2.179 cubic centimeters.

Let assume volume occupied by the water has a cube-like shape, whose side has the following measure:

$l = \sqrt[3]{2.179\,m^{3}}$

$l\approx 1.296\,cm$

6 0

2 years ago

Cos3A-sin3A/1-2sin2A= cosA + sinA. Prove the identity ​

Cos3A-sin3A/1-2sin2A= cosA + sinA. Prove the identity