Question

o is a point in the interior of a square abcd such that oab is an equilateral triangle show that ocd is an isosceles triangle

Answer 1

ΔOAB is equilateral triangle then

ln ΔAOD and ΔBOC

AD=BC (sides of the square)

∠DAO=∠CBD=300 (900−angleofequilateralΔ(600))

AO=OB (sides of equilateral of triangle)

ΔAOD≅ΔBOC (SAS criterion)

then OD=OC

So ΔCOD is an isosceles triangle