Function to find the length of the transverse common tangent
void lengthOfTangent ( double r1 , double r2 , double d ) { cout << " The ▁ length ▁ of ▁ the ▁ transverse " << " ▁ common ▁ tangent ▁ is ▁ " << sqrt ( pow ( d , 2 ) - pow ( ( r1 + r2 ) , 2 ) ) << endl ; }