Answer:
base = 15 units
Step-by-step explanation:
We are given area of a triangle = 52.5 sq. units
Height is given as 7 and we have to find the base.
Using formula for area of triangle:
Area of triangle = 
52.5 * 2 = base × 7
105 = base × 7
base = 15
Let x be the length of the train.
On the basis of the observer;
Speed of the train = x/6
On the basis of the bridge;
Total distance covered by any point of the train= 350+x
Speed = (350+x)/20
Equating the two expressions of speed;
x/6 = (350+x)/20
20(x) = 6(350+x)
20x = 2100+6x
(20-6)x = 2100
14x = 2100
x= 2100/14 = 150 m
Speed = x/6 = (350+x)/20 = 150/6 = 500/20 = 25 m/s.
Therefore,
Length of train = 150 m
Speed of train = 25 m/s
I hope this helps. Have a good day.
