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In a circle with center O and radius 1 cm, an arc AB makes an angle 60 degrees at O. Let R be the region bounded by the radii OA, OB and the arc AB. If C and D are two points on OA and OB, respectively, such that OC = OD and the area of triangle OCD is half that of R, then the length of OC, in cm, is
It is given that radius of the circle = 1 cm
Chord AB subtends an angle of 60Β° on the centre of the given circle.Β R be the region bounded by the radii OA, OB and the arc AB.
Therefore, R = $$\dfrac{60Β°}{360Β°}$$*Area of the circle =Β $$\dfrac{1}{6}$$*$$\pi*(1)^2$$ = $$\dfrac{\pi}{6}$$ sq. cm
It is given that OC = OD andΒ area of triangle OCD is half that of R. Let OC = OD = x.
Area of triangle COD = $$\dfrac{1}{2}*OC*OD*sin60Β°$$
$$\dfrac{\pi}{6*2}$$ = $$\dfrac{1}{2}*x*x*\dfrac{\sqrt{3}}{2}$$
$$\Rightarrow$$ $$x^2 = \dfrac{\pi}{3\sqrt{3}}$$
$$\Rightarrow$$ $$x$$ = $$(\frac{\pi}{3\sqrt{3}})^{\frac{1}{2}}$$ cm. Hence, option C is the correct answer.Β
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