Slant height of a pyramid

May 2010
5
1
The ratio of the height of the pyramid to the edge of the square base is 1.5 to 1. The height of the pyramid is 3 meters. What is the approximate length of the slant height of the pyramid?

A. 4.4 m
B. 3.2 m
C. 2.8 m
D. 1.4 m

I am not sure what the ratio part means, but I thought maybe
using a proportion
(1.5/1)=(3/x)
so x=2

and then using a triangle (pyth. thm.) 3^2 + 2^2 = c^2 (slant height)
so I got sqrt (13) which equals 3.6

which the answer is supposed to be 3.2 but I do not think I did this correct because the answers are not close enough.
 

dwsmith

MHF Hall of Honor
Mar 2010
3,093
582
Florida
The ratio of the height of the pyramid to the edge of the square base is 1.5 to 1. The height of the pyramid is 3 meters. What is the approximate length of the slant height of the pyramid?

A. 4.4 m
B. 3.2 m
C. 2.8 m
D. 1.4 m

I am not sure what the ratio part means, but I thought maybe
using a proportion
(1.5/1)=(3/x)
so x=2

and then using a triangle (pyth. thm.) 3^2 + 2^2 = c^2 (slant height)
so I got sqrt (13) which equals 3.6

which the answer is supposed to be 3.2 but I do not think I did this correct because the answers are not close enough.
2 is the length of base not the length of b in your triangle.