A girl of height 90cm is walking away from the base of a lamppost at a speed of 1.2m/s. If the lamp is 3.6 m above the ground, find the length of her shadow after 4 seconds.

A girl of height 90cm is walking away from the base of a lamppost at a

1.	A girl of height 90cm is walking away from the base of a lamppost at a speed of 1.2m/s. If the lamp is 3.6 m above the ground, find the length of her shadow after 4 seconds.
Answer» B Represent the lamp Post of height 3. 6m ⚫ The Girls Walk at a speed of 1. 2 m/s ⏩ In 4 Seconds She walks 4 × 1. 2 m = 4. 8 m And reaches D. ⏩ LET CD represent the girl of height 0.9 m and DE is her shadow of X METRE. Now, in ∆CDE and ∆ ABE ∆CDE = ∆ ABE... Each 90°E. = E Common=> ∆ CDE - ∆ ABE AA Similarity Criterion. => DE/BE = CD/AB ⏩ X/X+4. 8 = 0. 9/3. 6 ⚫ 4x = x + 4. 8 4x-x = 4. 8 3X. = 4. 8 X = 4. 8/3⏩ X. = 1. 6 m. So, length of the shadow after 4 seconds = 1. 6 m.