In the given figure, two concentric circles with centre O have radii 21 cm and 42 cm. If \[\angle AOB=~60{}^\circ \], find the area of the shaded region. [Use \[\pi =\frac{22}{7}\]] |
Answer:
Angle for shaded region \[=360{}^\circ -60{}^\circ =300{}^\circ \] Area of shaded region \[=\frac{\pi \theta }{360}({{R}^{2}}-{{r}^{2}})\] \[=\frac{22}{7}\times \frac{300}{360}[{{42}^{2}}-{{21}^{2}}]\] \[=\frac{22}{7}\times \frac{5}{6}\times 63\times 21\] = \[3465\,\,c{{m}^{2}}\]
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