Question

The altitute of two purpose station at A and B, 80km apart are respectively 225m and 550m. There is an intervening obstruction at point C, 40km from A, it has an elevation of 285m. Ascertain if A and B are intervisible, and if necessary, find how much, station at B should be raised so that line of sight must nowhere be less than 3m above the surface of the ground.​

Answer 1

Answer:

Let the speed of car starting from point A=x km/hr

The speed of car starting from point B=y km/hr

According to the first condition :The two cars travel in same direction-

speed⇒(x−y)

hr

km

∵speed=

time

distance

⇒x−y=

8

80

⇒x−y=10....eq1

According to the second condition :The two cars travel in opposite direction-

∵speed=

time

distance

⇒x+y=

3

4

80

⇒x+y=60....eq2

Adding eq1 and eq2

⇒2x=70⇒x=35

put x=35 in eq1

⇒35−y=60⇒y=25

Hence, the speed of car starting from point A=35km/hr

The speed of car starting from point B=25 km/hr.

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