# Tangent (kissing) circles on boundary of a larger circle

According to a this image there is a large circle with radius of $R$ and two smaller tangent (kissing) circles with radius of $R_c$ that are placed so that their centers are on the boundary of the larger circle. The dashed line crosses center of larger circle and the kissing point of smaller circles.

Is there a way to calculate $R_c$ according to $\theta$ and $R$?

• Is this question complete? – Harsh Kumar Apr 6 '17 at 10:33
• In fact the main problem has 8 smaller circles that are tangent to each other but it was very hard to draw for me so I simplified it. – arash.amd Apr 6 '17 at 10:38

If any of two are known then the third one can be found $$R_c=R\times\sin\theta$$