A rectangular bookcase 60 inches long and 30 inches wide. How long is the diagonal? Round to the nearest inch.

A.

52 inches

B.

67 inches

C.

76 inches

D.

81 inches

B

Since this is rectangular bookcase, we can apply Pythagorean theorem

for the right triangle. (Half of the rectangle is a right-triangle if you use the diagoal to divide it)

a^2+b^2=c^2

60^2+30^2=3600+900=4500=c^2

c=sqrt (4500) = 67.08