Question

RADHA KRISHNA PUBLIC SCHO
AFFILIATED TO CBSE NEW DELHI VIDEO
ASSIGNMENT CHAPTER -12 HERON'S
SUB
MO
NAME :
CLASS-IX
21. Find the area of the triangle whose sides are 12 cm, 16cm, and 20cm
22. A triangular park has sides 30m, 82m , and 56m. A gardener has to put a
irass inside it. How much area does he need to plant. Find the cost of fencing
2 Rs. Per metre. Leaving a space 4m wide for a Gate on one side.
3. The side of a triangle are 20 cm, 34 cm, and 42 cm. Find the area of the t
ongest altitude.
1. The cost of turfing a triangular field at the rate of 5 Rs. Per m.If the side
e sides of the field (V5 = 2.24)
Using Heron's formula. find the area of an equilateral triangle whose Pe
The base of an isosceles triangle measures 24 cm and its area 60 cm.Fin
Find the area of shaded region?​

Answer 1

✨Find the area of the triangle whose sides are $12cm$, $16cm$, and $20cm$.

Solution:

$\sqrt{s(s-a)(s-b)(s-c)}$  

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

In given triangle,

$s=\frac{12+16+20}{2}$=$s</p><p>[tex]\frac{48}{2}$

$=24</p><p>$

Thus area of given triangle =  $\sqrt{24(24-20)(24-12)(24-16)}$

$=\sqrt{24\times4\times12\times8}$

$=\sqrt{9216}$

$=96$

Therefore, area of a triangle whose sides are $12cm$, $16cm$, and $20cm$ is $=96cm^{2}$