The figure shows an ancient coin which was once used in China. The coin is in the shape of a circle of radius 3 cm with a square of sides cm removed from its centre. The area of each face of the coin is 77
cm.
() Form an equation in x and show that it reduces
to 20 - r=0.
(ii) Solve the equation 20 - = 0.
(in) Find the perimeter of the square.

Atriangle with all sides of equal length is a/an triangle. a. right b. scalene c. equilateral d. isosceles

Afactory makes propeller drive shafts for ships. a quality assurance engineer at the factory needs to estimate the true mean length of the shafts. she randomly selects four drive shafts made at the factory, measures their lengths, and finds their sample mean to be 1000 mm. the lengths are known to follow a normal distribution whose standard deviation is 2 mm. calculate a 95% confidence interval for the true mean length of the shafts. input your answers for the margin of error, lower bound, and upper bound.

Could somebody me with this radical simplification?