#1**+2 **

From his line of sight....we have that

tan (20) = height of street lamp from his line of sight / distance from streetlamp

tan (20) = height of streetlamp from his line of sight / 25 ..... multiply both sides by 25

25* tan (20) = height of streetlamp from his line of sight

So......the total height of the streetlamp =

6 + 25 * tan(20) ≈ 15 ft

CPhill Apr 24, 2019