Question

Q1. Jim stands beside a wide river and wonders how wide it is. He spots a large rock on the bank directly across from him. He then walks upstream 65 strides and judges that the angle between him and the rock, which he can still see, is now at an angle of 30° downstream Jim measures his stride to be about 0.8 m long. Draw a diagram. Estimate the width of the river.

Answer 1

Given, Jim walks upstream 65 strides and each stride is 0.8 m long.

So, net distance travelled by the Jim in upstream = 0.8 x 65 = 52 m

Let, the width of the river is 'x' .

So, the diagram can be drawn as :

Now, from the diagram

  

or,

or,

or,   

Hence, the width of the river is nearly 30 m.

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