Question 41811
 
The sum of the angles in a triangle is equal to 180 degrees.  The angles opposite to the equal sides are equal. 
 
  The top angle = 72 degrees.
 
  The sum of the other two angles = 180-72 = 108 degrees.
 
  Since both the angles are equal (Opp to sides of 15 cms), their angles are
 
  = 108/2 = 54 degrees each.  Answer.  I hope this is clear to you

gsm