Question

find the area of an equilateral triangle whose sides are 5 cm, 7cm and 9cm.​

Answer 1

Answer:

P = A+B+C

P = 5+7+9

P = 19cm

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Answer 2

first of all if its an equilateral triangle then all the sides will be equal

Assuming that its an ordinary triangle,

a=5cm, b=6cm, c= 7cm

Therefore,

Semiperimeter= (a+b+c)/2

= (5+6+7)/2

= 18/2

= 9

By Heron's formula,

Area of triangle = √{s(s-a)(s-b)(s-c)}

= √{9(9-5)(9-6)(9-7)}

= √(9*4*3*2)

= 3*2√(3*2)

= 6√6cm^2