4)The diagram shows a circle inside a semicircle. The semicircle ABC has centre O and radius 9 cm. The circle has diameter OB. Calculate, in cm2, the shaded area.

Give your answer to 3 significant figures.

Which statement is true about the extreme value of the given quadratic equation? a. the equation has a maximum value with a y-coordinate of -21. b. the equation has a maximum value with a y-coordinate of -27. c. the equation has a minimum value with a y-coordinate of -21. d. the equation has a minimum value with a y-coordinate of -27.