L A traflic signal board, iru:Ucating rSCHOOOL AHEAD: is an equilateral triangle with side 'a'. Find the area of the signal board, using Heron'sform '..la. If itsperimeter is 180 cm, what will be the area of the signal board?

Triangle is an equilateral triangle of side a. a + a + a 3a s = 2 = 2. Using Heron's formula, we get www .cbsepdf .com 86 MATHEMATIC&-IX Area of the triangle = 43: (3 - a)(3 -a)(3; -a) 3a a a a -x-x -x- .J3 a2 2 2 2 2 4 If perimeter = 180 cm, then side = 1!0 = 60 cm. .. Area of the triangle = .J3 x (60>2 = 900 .J3 cm2 4