The edges of a triangular board are `6cm,8cm" and "10cm` .The cost of painting it at the rate of `9` paise per `cm^(2)` is

Options

A. rupee 2.00
B. rupee 2.16
C. rupee 2.48
D. rupee 3.00

Answer

B

Explanation

(b) Since, the edges of a triangular board are `a = 6 cm, b=8 cm` and `c=10 cm.`
Now, semi-perimeter of a triangular board.
`s=(a+b+c)/(2)`
`=(6+8+10)/(2)=(24)/(2)=12 cm`
`"Now, area of triangular board"=sqrt(s(s-a)(s-b)(s-c)`
`=sqrt(12(12-6)(12-8)(12-10)`
`=sqrt(12xx6xx4xx2)`
`=sqrt((12)^(2)xx(2)^(2)`
`=12xx2=24 cm^(2)`
Since, the cost of painting for area 1 `cm^(2)=rupee 0.09`
`therefore` Cost of paint for area 24 `cm^(2)=0.09xx24`=rupee 2.16
Hence, the cost of triangular board is rupee `2.16.`