1.

A triangle has sides of length 6, 7 and 8. The line through its incenter parallel to the shortestside is drawn to meet the other two sides at P and Q. The length of the segment PQ is

Answer»

`12/5`
`15/4`
`30/7`
`33/9`

Solution :
Let AD=h , ID=x
AREA of triangle ABC=R.s
`=r((6+7+8)/2)`
`=21/2r` …(1)
Area of triangle `ABC=1/2BCxxh`
`=1/2(6)xxh=3h` …(2)
From (1) and ()
`"2lr"/2=3h`
`r/h=6/21=2/7`
TriangleABC and triangle APQ are similar
`therefore (PQ)/(BC)=(h-r)/h`
`(PQ)/6=1-r/h`
`(PQ)/6=1-2/7`
`rArr PQ=30/7`


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