Perimeter of a sector = 2r + \(\frac{\theta}{360^o}\) x 2 x \(\frac{22}{7}\) x 21 64 = 2 x 21 + \(\frac{\theta}{360^o}\) x 2 x \(\frac{22}{7}\) x 21 64 = 42 + \(\frac{\theta}{360^o}\) x 44 x 3 64 - 42 = \(\frac{\theta}{360^o}\) x 11 x 3 22 = \(\frac{33\theta}{90}\) \(\theta = \frac{22 \times 30}{11}\) = 60o