D32.5
15: A 5m long ladder is placed leaning
towards a vertical wall such that it
reaches the wall at a point 4m high.If foot
of ladder is moved 1.6m towards the
wall,then the distamce by which the top of
the ladder would slide upwards on the
wall is
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Answer:
distance the ladder slide upwards=7m
Step-by-step explanation:
length of ladder= 5m
height of wall till the ladder reaches= 4m
base= let it be x.
distance from wall to foot = x -1.6
distance the ladder slide upwards= let it be h .
by Pythagoras theorem
5²=x²+4²
25-16= x²
9= x²
√9= x
x= 3m.
therefore... now .
height = h+4m
base= 3-1.6=1.4m
length of ladder= 5m
by Pythagoras theorem
5²=( h+4)²+ 1.4²
25= h²+16+8h+1.96
25-16-1.96= h²+8h
7.04= h²+8h
h²+8h-7.04
h²+8h-7
h²+7h+h-7
h(h-7)+1(h-7)
h+1 and h-7
therefore h=7m
distance the ladder slide upwards=7m
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