Circular measure self-exercise 1.8 Q2 sukatan membulat latihan kendiri 1.8 form 5 add maths kssm

Circular measure self-exercise 1.8 Q2 sukatan membulat latihan kendiri 1.8 form 5 textbook add maths buku teks matematik tambahan kssm

In the diagram on the right are three identical 20 cent coins with the same radii and touching each other. If the blue coloured region has an area of 12.842 mm2, find the radius of each coin, in mm.

[mohammadfaiz]

This question is so hard.
Thx so much