







How many locations for the lampposts are possible? 
20070121 

From Madeeha: Maria's backyard has two trees that are 40 feet apart, as shown in the accompanying diagram. She wants to place lampposts so that the posts are 30 feet from both of the trees. Draw a sketch to show where the lampposts could be placed in relation to the trees. How many locations for the lampposts are possible? Answered by Penny Nom. 





The height of the lamppost 
20011002 

From Werner: I am working on question 51,section 3.7 ,page 191 of Stewart's Single Variable Calculus. The question involves a lamp post which is casting a shadow around the eliipse whose formula is x^{2} + 4*y^{2} = 5. I have found the derivative of the elllipse both explicitly: x/4(((5x^{2})/4)^{0.5}) and implicitly : y' =  x/(4*y). Answered by Harley Weston. 





A lampost and its shadow 
20001224 

From Laura: A lamppost line EC casts a shadow line AC. A 30 cm ruler line DB has been moved from A so that it's shadow falls just within the shadow of the lamppost.  Suppose the length of the ruler's shadow is 42 cm. What is the slope of the imaginary line AE?
 Suppose the lamppost's shadow is 15 m. long. How tall is the lamppost?
Answered by Penny Nom. 

