A street light bulb is fixed on a pole 6 m above the level of the street. If a woman of height 1.5 m casts a shadow of 3 m, find how far she is away from the base of the pole.
Let A be the position of the street bulb fixed on a pole AB = 6 m and CD = 1.5 m be the height of a woman and her shadow be ED = 3 m.
Let distance between pole and woman be x m.
Here, woman and pole both are standing vertically.
So, CD || AB
In ΔCDE and ΔABE,
∠E = ∠E ......[Common angle]
∠ABE = ∠CDE ......[Each equal to 90°]
∴ ΔCDE ∼ ΔABE .....[Bt AAA similarity criterion]
Then, `(ED)/(EB) = (CD)/(AB)`
⇒ `3/(3 + x) = 15/6`
⇒ `3 xx 6 = 1.5(3 + x)`
⇒ `18 = 1.5 xx 3 + 1.5x`
⇒ `15=.5x = 18 - 4.5`
∴ `x = (13.5)/1.5` = 9 m
Hence, she is at the distance of 9 m from the base of the pole.