Johnny, while playing in his garden, wondered how he could measure the height of an old spruce, without climbing it up. He saw a shadow of the old spruce firmly marked on the lawn and decided to use the physical phenomenon he saw. To take advantage of the similarity of triangles, he positioned himself so that the end of his shadow and the end of the tree’s shadow were in the same place. Determine the height of the tree accurate to within one decimeter. The data: the shadow’s length of the tree is 18.5 m, Johnny’s height is 166 cm and the length of Johnny’s shadow is 2.40 m.
The height of the tree is:
[m] [cm] [dm]
HELP 1
HELP 2
HELP 3
Maximum score: 10/10
`(DC)/(BA)=(OC)/(OA)`
`(DC)/(OC)=(BA)/(OA)`
`(BD)/(BA)=(DC)/(AC)`
`(BO)/(OA)=(DC)/(BA)`
`DC=(18.5*1.66)/(2.4)`
`DC=(18.5*2.40)/(1.66)`
`DC=(1850*166)/(24)`
`DC=(185*16.6)/(24)`