+0  
 
0
96
1
avatar

A circular cylindrical post with a circumference of 4 feet has a string wrapped around it, spiraling from the bottom of the post to the top of the post. The string evenly loops around the post exactly four full times, starting at the bottom edge and finishing at the top edge. The height of the post is 15 feet. What is the length, in feet, of the string?

 Nov 26, 2020
 #1
avatar+116126 
+1

If  we could "unroll"  the cylinder  we  would  have  a rectangle  with a width of 4 ft and a height  of  15  ft

 

The diagonal  of  this rectangle  represents the  length of the  string  and it is just the  hypotenuse of a right triangle with legs of 4 and  15

 

Its length  =    sqrt  (4^2  + 15^2 )  =  sqrt  ( 16 + 225)  =  sqrt (441)  =  21 feet

 

 

cool cool cool

 Nov 26, 2020

78 Online Users

avatar
avatar
avatar
avatar
avatar
avatar