Why does cos x equal cos -x?

Updated: 12/14/2022
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cos x equals cos -x because cos is an even function. An even function f is such that f(x) = f(-x).

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Q: Why does cos x equal cos -x?
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What is Cos squared x equal to?

Cos^2 x = 1 - sin^2 x

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You can look up "trigonometric identities" in Wikipedia.Cos(2x), among other things, is equal to (cos x)^2 - (sin x)^2 If you meant cos squared x, or (cos x)^2, that is equal to (1 + cos(2x))/2

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One solution. (cos x)2 - 2cos x = 3 Factor: (cos x - 3)(cos x + 1)= 0 cos x = {-1, 3} Solve: For cos x = -1, x = 180 deg No solution for cos x = 3

Why does the derivative of sin x equal - cos x?

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What does cos squared x - Sin squared x equal?

2 x cosine squared x -1 which also equals cos (2x)

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Cos plus tansin equals sec?

Start on the left-hand side. cos(x) + tan(x)sin(x) Put tan(x) in terms of sin(x) and cos(x). cos(x) + [sin(x)/cos(x)]sin(x) Multiply. cos(x) + sin2(x)/cos(x) Make the denominators equal. cos2(x)/cos(x) + sin2(x)/cos(x) Add. [cos2(x) + sin2(x)]/cos(x) Use the Pythagorean Theorem to simplify. 1/cos(x) Since 1/cos(x) is the same as sec(x)- the right-hand side- the proof is complete.

How does sin2x divided by 1-cosx equal 1 plus cosx?

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What does Sin squared x Cos squared x equal?

sin2 x = (1/2)(1 - cos 2x) cos2 x = (1/2)(1 + cos 2x) Multiplying both you get (1/4) (1 - cos2 2x) Which is equal to (1/4) (1 - (1/2) (1 + cos 4x) = (1/8) (2 - 1 - cos 4x) = (1/8) (1 - cos 4x) Or If it is the trigonomic function, sin squared x and cosine squared x is equal to one

Why does the derivative of sin x equal cos x reason not prove?

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What is the exact solution to cosx equals sin2x?

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