Question

In an equilateral triangle ABC if AB=20 cm find its area.​

Answer 1

Answer:

Answer

Correct option is

D

129.75cm2

△ABC and △EBD are equilateral triangles. So, all their sides will be equal.

In △ABC, 

AB=BC=AC=20 cm      ...(Given)

 Area of △ABC=43a2

=43(202)=43×400=3×100

=1.73×100=173           ...( Given3=1.73)

In △EBD, 

EB=BD=ED=10 cm          ...(As D is mid point of BC and divides the line BC equally into BD and DC)

Area of △EBD=43a2

=43(102)=43×100=3