If S is the switch angle and is diamond angle, r is the radius of slip, the distance between middle point slip and the nose of obtuse crossing, is

• A. <img src="/_files/images/civil-engineering/railways/61-17-174-1.png">
• B. <img src="/_files/images/civil-engineering/railways/61-17-174-2.png">
• C. <img src="/_files/images/civil-engineering/railways/61-17-174-3.png">
• D. <img src="/_files/images/civil-engineering/railways/61-17-174-4.png">