2. You can calculate the area of triangle if you
know the length of all three sides, using a
formula that has been known for nearly 2000
years.
It is called “Heron’s Formula” after hero of
Alexandria
3. a b
c
area of triangle = √s(s-a)(s-b)(s-c)
; s = (a+b+c)/2
4. Step1 : identify the three sides a,b,c
Step2 : find the perimeter
Step3 : find half of the perimeter , s
Step4 : find (s-a) , (s-b) and (s-c)
Step5 : multiply s with step4
Step6 : square root of step5
5. Find the area of triangle ABC with AB=7cm,
BC=8cm and AC=9cm ?
Ans: perimeter = (7+8+9) = 24 cm
s = 24/2 =12
s-a = 12-7 =5
s-b = 12-8 =4
s-c = 12-9 =3
s(s-a)(s-b)(s-c) = 12*5*4*3 =720
Area of triangle ABC =√720 = 12√5 sq.cm
6. Find the area of triangle with sides 3cm, 4cm
and 5cm ?
Ans: perimeter = (3+4+5) = 12 cm
s = 12/2 =6
s-a = 6-3 =3
s-b = 6-4 =2
s-c = 6-5 =1
s(s-a)(s-b)(s-c) = 6*3*2*1 =36
Area of triangle ABC =√36= 6 sq.cm
