Question

please solve soon with formula​

Answer 1

Edges of Triangular board:

6cm , 8cm , 10 cm

Let, 6cm = a , 8cm = b, and 10cm = c

So,

Semi-perimeter = half the sum of all the three sides

☛ s = (a + b + c )/ 2

☛ s = (6+8+10) / 2

☛ s = 24/2

☛ s = 12cm

Now, By Heron's formula,

$\sf Area \: of \: a \: \Delta ABC = \sqrt{s(s - a)(s - b)(s - c)}$

So, Applying the Heron's formula on this triangle, we get the area as:

$\\ \\ \sf \rightarrow \quad \sqrt{12(12 - 6)(12 - 8)(12 - 10)} \\ \\ \sf \rightarrow \quad \sqrt{12 \times 6 \times 4 \times 2} \\ \\ \sf \rightarrow \quad \sqrt{ {2}^{2} \times 3 \times 3 \times 2 \times {2}^{2} \times 2} \\ \\ \sf \rightarrow \quad \sqrt{ {2}^{2} \times {3}^{2} \times {2}^{2} \times {2}^{2} } \\ \\ \sf \rightarrow \quad 2 \times 3 \times 2 \times 2 \\ \\ \sf \rightarrow \quad 24 \: {cm}^{2}$

So, We get area as 24 cm²

Now,

Rate of painting = 9 paise / cm²

Cost = Area × Rate of painting

☛ Cost = 24 × 9

☛ Cost = 216 paise

Now, Convert the cost into Rupees

☛ 1 Rupee = 100 Paise

So,

Cost = 216 /100

Cost = 2.16 Rupees

Hence, Second Option is correct.