Discover the Double Angle Formula for Cosine and Simplify Trigonometric Expressions with Cos²(x)

cos^2x (Power to Double Angle)

1/2(1+cos2x)

The double angle formula for cosine states that:

cos(2x) = cos²(x) – sin²(x)

Now, if we rearrange this equation, we can solve for cos²(x) in terms of cos(2x) and sin²(x):

cos²(x) = cos²(2x)/2 + sin²(x)/2

We can replace sin²(x) with 1 – cos²(x), since sin²(x) + cos²(x) = 1:

cos²(x) = cos²(2x)/2 + (1-cos²(x))/2

Simplifying this equation, we get:

cos²(x) = (1/2)*(cos²(2x) + 1)

Therefore, the formula for cos²(x) in terms of double angle is:

cos²(x) = (1/2)*(cos²(2x) + 1)

This formula can be used to simplify trigonometric expressions involving cos²(x) in terms of the double angle formula.

More Answers:
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