Question

Find the cost of laying grass in a triangular field 50cm, 65cmand65mat the rate of rs.7 per m2

Answer 1

sorry mistake from my side...apologies

Answer 2

We have sides of triangular field  = 55 m  , 65 m and 65 m

We know heron's formula :

Area of triangle  = s(s −a)(s −b)(s −c)−−−−−−−−−−−−−−−−−−√

Here s  = a + b + c2 and a =  50  , b  =  65 and c = 65

So,

s  = 50 + 65+ 652 = 1802 = 90
Then

Area of triangular field  = 90(90 −50)(90 −65)(90 −65)−−−−−−−−−−−−−−−−−−−−−−−−−√ = 90× 40 × 25 × 25−−−−−−−−−−−−−−−−√ = 2250000−−−−−−−√ = 1500 m2 
And

Rate of laying grass =  Rs. 7 per m2
So,

Cost of laying grass in triangular field  =   7 × 1500 =  Rs . 10500