MathematicsMedium94×since 2002Q2855Let Δ\DeltaΔ be the area of the region {(x,y)∈R2:x2+y2≤21,y2≤4x,x≥1}\left\{ {(x,y) \in {R^2}:{x^2} + {y^2} \le 21,{y^2} \le 4x,x \ge 1} \right\}{(x,y)∈R2:x2+y2≤21,y2≤4x,x≥1}. Then 12(Δ−21sin−127){1 \over 2}\left( {\Delta - 21{{\sin }^{ - 1}}{2 \over {\sqrt 7 }}} \right)21(Δ−21sin−172) is equal toA23−132\sqrt 3 - {1 \over 3}23−31B23−232\sqrt 3 - {2 \over 3}23−32C3−43\sqrt 3 - {4 \over 3}3−34D3−23\sqrt 3 - {2 \over 3}3−32Check answerSkip