The perimeter of an isosceles triangle is [[$ 15 \;\text{cm} $]]. Its sides are [[$ 1,5 \;\text{cm} $]] longer than the base. Calculate the area of the triangle. (Source: Finnish matriculation exam, spring 2000)

Take a picture of your solution and return it to the submission folder.

Answer: The area of the triangle is cm[[$ ^2 $]].