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If the difference between an exterior an...

If the difference between an exterior angle of a regular polygon of 'n' sides and an exterior angle of another regular polygon of `'(n+1)'` sides is equal to `5^(@)`, find the value of 'n'.

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To solve the problem, we need to find the value of 'n' such that the difference between the exterior angle of a regular polygon with 'n' sides and that of a regular polygon with '(n+1)' sides is equal to 5 degrees. ### Step-by-Step Solution: 1. **Understand the formula for the exterior angle of a polygon**: The exterior angle of a regular polygon with 'n' sides is given by the formula: \[ \text{Exterior angle} = \frac{360}{n} \] Similarly, for a polygon with '(n+1)' sides, the exterior angle is: \[ \text{Exterior angle} = \frac{360}{n+1} \] 2. **Set up the equation for the difference**: According to the problem, the difference between the exterior angles of the two polygons is 5 degrees: \[ \frac{360}{n} - \frac{360}{n+1} = 5 \] 3. **Simplify the equation**: To simplify the left-hand side, we can find a common denominator: \[ \frac{360(n+1) - 360n}{n(n+1)} = 5 \] This simplifies to: \[ \frac{360}{n(n+1)} = 5 \] 4. **Cross-multiply to eliminate the fraction**: Cross-multiplying gives us: \[ 360 = 5n(n+1) \] 5. **Rearranging the equation**: Dividing both sides by 5: \[ 72 = n(n+1) \] 6. **Form a quadratic equation**: Rearranging gives: \[ n^2 + n - 72 = 0 \] 7. **Factor the quadratic equation**: We need to factor the quadratic equation. We look for two numbers that multiply to -72 and add to 1. The numbers are 9 and -8: \[ (n - 8)(n + 9) = 0 \] 8. **Solve for 'n'**: Setting each factor to zero gives: \[ n - 8 = 0 \quad \Rightarrow \quad n = 8 \] \[ n + 9 = 0 \quad \Rightarrow \quad n = -9 \quad (\text{not valid since } n \text{ must be positive}) \] 9. **Conclusion**: Therefore, the value of 'n' is: \[ n = 8 \]
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