To solve this, let us first imagine a smaller triangle
created by the head of Jim (A), the top of the lamp post (B), and somewhere on
the body of the lamp post which is directly perpendicular to the head of Jim
(C).
CB = 16 – 6 = 10 ft
AC = 4 ft
Calculate for angle B using tan function:
tan B = AC / CB
B = tan^-1 (4 / 10)
B = 21.8°
Now imagine a bigger triangle created by the tip of
shadow (D), the top of the lamp post (B), and the base of the lamp post (E).
BE = 16 ft
B = 21.8°
We can calculate for DE using tan function:
tan B = DE / BE
(16 ft) tan 21.8 = DE
DE = 6.4 ft
Since Jim is 4ft away from the base of the lamp post,
therefore the length of the shadow is:
6.4 ft – 4 ft
= 2.4 ft
Therefore the length of Jim’s shadow is 2.4 ft long
