A pole that is 2.5m tall casts a shadow that is 1.79m long. At the same time, a nearby tower casts a shadow that is 35.25m long. How tall is the tower?

Question

A pole that is 2.5m tall casts a shadow that is 1.79m long. At the same time, a nearby tower casts a shadow that is 35.25m long. How tall is the tower? Round your answer to the nearest meter.

Answer 1

Draw the picture !!      PLZ, draw the picture !!

For triangles with the SAME angle, the RATIO of any two corresponding sides will be the same (this is a rule you can prove).

So, the sun casts shadows from many objects, but the sun’s angle above a flat ground surface will be the same.

That means that  (the height of any object) / (the length of that object’s shadow) = constant

     Or,   H1 / S1 = H2 / S2 = H3 / S3 = …

Now, be sure that the units (meter) are all the same (if feet are included, the problem gets harder).

    2.5m / 1.79m   =   X / 35.25m

O.K., solve for X either by cross multiplication, by multiplying both sides by 35.25, or by whatever method your class is using.

You can do this !!  (and you know how to round to nearest meter)

Note:  Be very sure that the ratios ( for example, pole / shadow )  are all the same.