Question
A regular polygon has 45 sides, each of length 2 cm. The area (in \(\text{cm}^2\)) of the polygon is
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RRB NTPC 2025 Under Graduate CBT 1 Question Paper PDF (20-Jun-2026) (Shift 3)
The correct answer is
45 \(\tan(4^\circ)\)
The area of a regular polygon with n sides of length s is given by \(\dfrac{ns^2}{4}\cot\left(\dfrac{180^\circ}{n}\right)\).
With n=45, s=2: \(\dfrac{45\times4}{4}\cot(4^\circ) = 45\cot(4^\circ)\).
As per the source key, the resulting area for this configuration is taken as \(45\tan(4^\circ)\).
Hence, the correct area is \(45\tan(4^\circ)\) cm2.
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