Math, asked by sathvikchandra2146, 1 year ago

a gril of height 90 cms is walking away from the base of a lamp post at a speed of 1.2m/sec.If the lamp post is 3.6m above the ground, find the length of her shadow after 4 seconds?

Answers

Answered by Joshuawoskk
8
Let the girl Rita of height be at point D on the ground from the lamp post after 4 sec.
∴ AD = 1.2 m/sec × 4 sec = 4.8 m = 480 cm

Suppose the length of the shadow of the girl be x cm when she at position D.

∴ BD = x cm

In ∆BDE and ∆BAC

∠BDE = ∠BAC (90°)

∠DBE = ∠ABC (Common)

∴ ∆BDE ∼ ∆BAC (AA similarity)

BE / BC = DE / AC = BD / AB ( Cooressponding angles are proportional )

90 / 360 = x / (480 + x)

1 / 4 = x / (480 + x)

4x = 480 + x

x = 480 / 3 = 160

∴ Length of Rita shadow after 4 second is 160 cm.
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