Question

if the side of the equilatral triangle is decreased by 20%,its area is decreased by

Answer 1

Answer:

36%

Step-by-step explanation:

Let the side of an equilateral triangle be a.

Area is √3/4 a²

decreased by 20% ( 1-(1 x 0.2))a =0.8a

Now, the side becomes 0.8a,

New Area = √3/4 (0.8a)² = √3/4 0.64a²

% change = (New -Old)/Old x 100

= √3/4 a² (1 -0.64) / √3/4 a²  x 100

= 0.36 x 100

=36%