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3 years ago

HELPPPP Cos x cosy = 1/2(sin (x+y)+ sin (x-y)) true or false

Mathematics

1 answer:

julsineya [31]3 years ago

8 0

Answer:

Step-by-step explanation:

REcall that sin(a+b) = sin(a)cos(b)+cos(a)sin(b). Then

sin(a+b)+sin(a-b) = sin(a)cos(b)+cos(a)sin(b) + sin(a)cos(b) -cos(a)sin(b) = 2sin(a)cos(b). Then

sin(a)cos(b) = (1/2)(sin(a+b)+sin(a-b))

So it is false

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93+(68+7)= 168

Step-by-step explanation:

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2 years ago

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3 years ago

Integrate the following

enot [183]

I suppose you mean to have the entire numerator under the square root?

$\displaystyle\int_2^4\frac{\sqrt{x^2-4}}{x^2}\,\mathrm dx$

We can use a trigonometric substitution to start:

$x=2\sec t\implies\mathrm dx=2\sec t\tan t\,\mathrm dt$

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$\displaystyle\int_0^{\pi/3}\frac{\sqrt{(2\sec t)^2-4}}{(2\sec t)^2}(2\sec t\tan t)\,\mathrm dt=\int_0^{\pi/3}\frac{\tan^2t}{\sec t}\,\mathrm dt$

We can write

$\dfrac{\tan^2t}{\sec t}=\dfrac{\frac{\sin^2t}{\cos^2t}}{\frac1{\cos t}}=\dfrac{\sin^2t}{\cos t}=\dfrac{1-\cos^2t}{\cos t}=\sec t-\cos t$

so the integral becomes

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3 years ago

What is the value of 0.5 + 0.3? Write your answer as a fraction in lowest terms.

Nikitich [7]

Answer:

4/5

Step-by-step explanation:

=.8

.8 into a fraction is 4/5

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3 years ago

Read 2 more answers