Math

Question Write the expression as a function of xx: cos(π4x)\cos\left(\frac{\pi}{4}-x\right).

Studdy Solution

STEP 1

1. The expression cos(π4x)\cos \left(\frac{\pi}{4}-x\right) involves the cosine function, which is a trigonometric function.
2. The angle subtraction formula for cosine can be used to simplify the expression: cos(AB)=cosAcosB+sinAsinB\cos(A-B) = \cos A \cos B + \sin A \sin B.
3. The values of cos(π4)\cos \left(\frac{\pi}{4}\right) and sin(π4)\sin \left(\frac{\pi}{4}\right) are known and equal to 22\frac{\sqrt{2}}{2}.

STEP 2

1. Apply the cosine angle subtraction formula.
2. Substitute the known values of cos(π4)\cos \left(\frac{\pi}{4}\right) and sin(π4)\sin \left(\frac{\pi}{4}\right).
3. Simplify the expression to get the function of xx.

STEP 3

Apply the cosine angle subtraction formula to cos(π4x)\cos \left(\frac{\pi}{4}-x\right).
cos(π4x)=cos(π4)cos(x)+sin(π4)sin(x) \cos \left(\frac{\pi}{4}-x\right) = \cos \left(\frac{\pi}{4}\right) \cos(x) + \sin \left(\frac{\pi}{4}\right) \sin(x)

STEP 4

Substitute the known values of cos(π4)\cos \left(\frac{\pi}{4}\right) and sin(π4)\sin \left(\frac{\pi}{4}\right) into the formula.
cos(π4x)=22cos(x)+22sin(x) \cos \left(\frac{\pi}{4}-x\right) = \frac{\sqrt{2}}{2} \cos(x) + \frac{\sqrt{2}}{2} \sin(x)

STEP 5

Simplify the expression by combining the terms with a common factor.
cos(π4x)=22(cos(x)+sin(x)) \cos \left(\frac{\pi}{4}-x\right) = \frac{\sqrt{2}}{2} (\cos(x) + \sin(x))
The final expression as a function of xx, with no angle measure involved, is:
cos(π4x)=22(cos(x)+sin(x)) \cos \left(\frac{\pi}{4}-x\right) = \frac{\sqrt{2}}{2} (\cos(x) + \sin(x))

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