Question

LENGHT OF SIDES OF A TRAINGLE ARE 10 CMS, 18 CMS, AND PERIMETER IS 42 CMS. FIND ITS AREA *

21 ROOT 11 SQUARE CM

41 ROOT 11 SQUARE CM

21 ROOT 41 SQUARE CM​

Answer 1

Ans:- Let length of third side of triangle= x cm

= length of first side = 10 cm

= length of second side = 18 cm

= perimeter of triangle = 42 cm

= therefore length of third side = perimeter of triange - sum of other two side of triangle

= 42 - (10 + 18)

= 42 - 28 = 14 cm

Now Semiperimeter of triangle = 42/2 = 21 cm

Now,

let a = 10cm, b = 18cm, c = 14cm

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

= √21(21 - 10)(21 - 18)(21 - 14)

= √21 × 11 × 3 × 7

= √21 × 21 × 11

= 21√11 cm^2

hence the right answer is 21√11 cm^2

hope it will help you