Question

there is a river in a village.the villagers want to measure its breadth without crossing the river as force of water 's current is very high

Answer 1

Answer:

Consider AB as the breadth of the river. Take a point M at a distance from B. Draw a perpendicular from the point M and name it as N so that it joins the point A as a straight line.

Now in △ABO and △NMO

We know that

∠OBA=∠OMN=90

∘

We know that O is the midpoint of the line BM

So we get

OB=OM

From the figure we know that ∠BAO and ∠MON are vertically opposite angles

∠BAO=∠MON

By ASA congruence criterion

△ABO≅△NMO

AB=NM(c.p.c.t)

Therefore, MN is the width of the river.