The number of solution the equation `cos(theta).cos(pitheta)=1` has 0 (b) 2 (c) 4 (d) 2

Explanation

To find the number of solutions for the equation \( \cos(\theta) \cdot \cos(\pi \theta) = 1 \), we can follow these steps:

### Step 1: Understand the equation
The equation \( \cos(\theta) \cdot \cos(\pi \theta) = 1 \) implies that both \( \cos(\theta) \) and \( \cos(\pi \theta) \) must equal either 1 or -1, since the product of two cosines can only equal 1 if both are 1 or both are -1.

### Step 2: Analyze the conditions
1. **Condition 1**: \( \cos(\theta) = 1 \)
- This occurs when \( \theta = 2n\pi \) for any integer \( n \).
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