Question

please solve it by heron's formula​

Answer 1

side a = 9 m

side b = 9 m

side c = 12 m

semi perimeter = (a+b+c)/2 = (9+9+12)/2 = 30/2 = 15

heron's formula ⇒ √s×(s-a)×(s-b)×(s-c)

√15×(15-9)×(15-9)×(15-12)

⇒ √15×6×6×3

⇒ √3×5×2×3×2×3×3

⇒ 18√5 m²

therefore, the area of the triangular entrance is 18√5 m²

cost for 1 m² = 750/-

cost for 18√5 m² = 30,186.91769624716/-

Answer 2

Given:

sides of the triangle are 9, 9, 12 m

Solution:

Herons formula =

$\sqrt{ \frac{perimeter}{2} } (a)(b)(c)$

perimeter = 9+9+12

= 30

a = 9

b = 9

c = 12

Area =

$\sqrt{ \frac{30}{2} (9)(9)(12)}$

$\sqrt{15(9)(9)(12)}$

$\sqrt{14580}$

$120.74....$

cost of tiling = 750 rs per metre square

= (750 × 120) + (750 × 75/100)

= 90, 000 + 562.5

= 90, 562.5 rupees