Show \(\cos \left(360^{\circ}-\theta\right)=\cos \theta\)

Short Answer

Expert verified
Question: Prove that the cosine of an angle difference (360° - θ) is equal to the cosine of the original angle (θ). Answer: Based on our calculations, we proved that \(\cos(360^{\circ} - \theta)=\cos(\theta)\) using the angle difference formula for cosine.

Step by step solution

01

Write the angle difference formula for cosine

Recall that the angle difference formula for cosine is: \(\cos(a - b)=\cos a \cos b + \sin a \sin b\).
02

Substitute the given values into the formula

Let's substitute \(a=360^{\circ}\) and \(b=\theta\) into the formula: \(\cos(360^{\circ} - \theta)=\cos(360^{\circ})\cos(\theta) + \sin(360^{\circ})\sin(\theta)\).
03

Evaluate the cosine and sine of 360°

We know that \(\cos(360^{\circ})=1\) and \(\sin(360^{\circ})=0\). Let's substitute these values into the expression: \(\cos(360^{\circ} - \theta)=1\cdot\cos(\theta) + 0\cdot\sin(\theta)\).
04

Simplify the expression

Now, we simplify the expression: \(\cos(360^{\circ} - \theta)=\cos(\theta)\). Therefore, we have demonstrated that \(\cos(360^{\circ} - \theta)=\cos(\theta)\).

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