2 The curve \(y = x ^ { 2 } - \frac { a } { x }\) has a stationary point at \(( - 3 , b )\).
Find the values of the constants \(a\) and \(b\).
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The diagram shows a sector of a circle, centre \(O\), where \(O B = O C = 15 \mathrm {~cm}\). The size of angle \(B O C\) is \(\frac { 2 } { 5 } \pi\) radians. Points \(A\) and \(D\) on the lines \(O B\) and \(O C\) respectively are joined by an arc \(A D\) of circle with centre \(O\). The shaded region is bounded by the \(\operatorname { arcs } A D\) and \(B C\) and by the straight lines \(A B\) and \(D C\). It is given that the area of the shaded region is \(\frac { 209 } { 5 } \pi \mathrm {~cm} ^ { 2 }\).
Find the perimeter of the shaded region. Give your answer in terms of \(\pi\).
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