When the shadow of a flagpole is 31.2m long a 1.6m fencepost casts a shadow 2.6m long how tall is the flagpole?
First, find the ratio of fencepost-height : shadow which is 1.6
: 2.6 . This can also be written as a fraction, 1.6/2.6 . Then,
multiply the flagpole's shadow by this ratio:
31.2 x 1.6/2.6 = 19.2
The flagpole is 19.2m high.
The trigonometry way:
On the imaginary right angled triangle formed by the fencepost
and its shadow, let the angle at which the hypotenuse meets the
ground = θ
sinθ = 1.6/2.6
sinθ = /31.2
x/31.2 = 1.6/2.6
2.6x = 31.2 * 1.6 = 49.92
x = 19.2
The flagpole is 19.2m high.