Question

4. The sides of a triangular field are 26 m, 28 m and
30 m. Find the cost of planting grass in the field at
* 4 per sq m. If a space of 5 m is to be left for the
gate to enter the field, find the cost of fencing it at
16 per metre.​

Answer 1

Sides of triangular field:26m,28m,30m

USING HERON's FORLULA

s=perimeter÷2

=(26+28+30)÷2

=84÷2=42m

Area =[s(s-a)(s-b)(s-c)]^1/2

=[42(42-26)(42-28)(42-30)]^1/2

=[42(16)(14)(12)]^1/2

=(6×7×4×4×2×7×2×6)^1/2

=6×7×4×2=336 sq.m

Cost of planting glass at 1sq.m=rupees4

Cost of planting grass at 336sq.m=4×336=1344rupees

Total length of sides on which fencing is done = perimeter-5m

=84-5=79m

Cost of fencing 1m=rupees16

Cost of fencing 79m=16×79=1264rupess

Hope it will help u