L = θ360×2πr\;\frac{\theta}{360} \times 2 \pi r360θ×2πr
22 = θ360×2× 227×15\;\frac{\theta}{360} \times 2 \times \;\frac{22}{7} \times 15360θ×2×722×15
θ=22 × 360 × 72 × 22 × 15\theta = \frac{22\;\times\;360\;\times\;7}{2\;\times\;22\;\times\;15}θ=2×22×1522×360×7
θ\thetaθ = 84∘^{\circ}∘
