10th Class Mathematics Areas Related to Circles Question Bank MCQs - Areas Related to Circles

  • question_answer
    Find the area of sector of central angle \[x{}^\circ \] of a circle with radius 4r.

    A) \[\frac{\pi x{{r}^{2}}}{45{}^\circ }\]

    B) \[\frac{2\pi x{{r}^{2}}}{360{}^\circ }\]

    C) \[\frac{2\pi x{{r}^{2}}}{45{}^\circ }\]

    D) \[\frac{4\pi x{{r}^{2}}}{180{}^\circ }\]

    Correct Answer: C

    Solution :

    Area of the sector with central angle \[\theta \] and radius r is \[\frac{\theta }{360{}^\circ }\times \pi {{r}^{2}}\] Here, radius is 4r and angle \[x{}^\circ \]. \[\therefore \] Area of sector \[=\frac{x{}^\circ }{360{}^\circ }\times \pi {{\left( 4r \right)}^{2}}\] \[=\frac{16\pi x{{r}^{2}}}{360{}^\circ }\] \[=\frac{2\pi x{{r}^{2}}}{45{}^\circ }\]


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