Question

In NCERT book of mathematics class9,optional exercise of areas of parallelogram and triangles is important for exam purpose SA2?

Answer 1

Yes,it is important from the examination point of view.
You can find its solutions in the RD Sharma book

Answer 2

it's just for your practice..if your concept is clear you'll do it easily and if not then just focus on concept making by practising on mandatory exercises.

hope you'll find it helpful.