Question

the edges of a triangular board are 6 cm, 8 cm and 10 cm . calculate the cost of painting it at the rate of 9 paise per cm²

Answer 1

Answer:

this is a right angle triangle

therefore area=1/2 * b * h

= 1/2 *6 *8

=24 cm square

cost per cm square= 9 paise

therefore 9*24 = 2 rupees 16 paise

Answer 2

GIven,

Edges of a triangular board are 6 cm, 8 cm, and 10 cm.

Cost of painting 1$cm^{2}$ = 9 paisa

To Find,

Cost of painting triangular board=?

Solution,

By heron's formula, we have

$s = \frac{ a+b+c}{2}$

where s is half of the triangle perimeter and a, b,c are edges.

Putting values in the formula,

$s = (6+8+10) /2$

$s = 24/2$

s = 12cm

Therefore, from the formula of the area of the triangle we have,

$A = \sqrt{( s(s-a)(s-b)(s-c) )}$

Putting values in this formula,

$A = \sqrt{( 12(12-6)(12-8)(12-10) )}$

$A = \sqrt{( 12(6)(4)(2) )} = \sqrt{24 *24$

$A = 24 cm^2$

Cost of painting 1 $cm^{2}$ = 9 paise

Cost of painting 24 $cm^{2}$ = 24*9 = 216 paise  = Rs. 2.16

Hence, the cost of painting a triangular board at the rate of 9 paise per cm² is Rs. 2.16.