Question

Find the height, h, of the cylinder. The radius, r, is 5 cm and the diagonal, d, is 15 cm. Round the answer to the nearest tenth.
A. 18.0 cm
B. 15.8 cm
C. 11.2 cm
D. 14.1 cm

Answer 1

The diagonal, height, and diameter form a right triangle: d^2 = h^2 + (2r)^2.
So h^2 = d^2 − (2r)^2 = 15^2 − 10^2 = 225 − 100 = 125.
h = sqrt(125) = 5√5 ≈ 11.2 cm.

Answer: C.