# Arc solutions

To calculate an arc or to compute points on an arc, tap and select Cogo / Arc solutions.

To calculate arc solutions

You can calculate an arc when two parts of the arc are known.

1. In the Arc values group, use the two Method fields to set the entry type for the arc values you have.

   The first known part of the arc is defined by one of the following:

   - Radius – is the radius of the arc.
   - Delta – is the delta or deflection angle.
   - Degree arc – is the deflection angle (delta) that results in an arc length of 100 units.
   - Degree chord – is the deflection angle (delta) that results in a chord length of 100 units.

   The second known part of the arc is defined by one of the following:

   - Delta – is the delta or deflection angle.
   - Length – is the arc length.
   - Chord – is the chord length.
   - Tangent – is the distance from the PC or PT to the PI.
   - External – is the shortest distance between the Point of Intersection (PI) and the arc.
   - Mid ordinate – is the distance between the arc and the chord at the mid point of the arc.

2. Tap Calc.

   The results for the horizontal arc, and a graphical representation of the arc are shown. Entered data appears as black text; computed data appears as red text.

Results

The following values are computed for an arc.

Item | Value | Definition
--- | --- | ---
1 | Segment area | The area between the arc and the chord.
2 | Sector area | The area between the arc and the two edge radii.
3 | Fillet area | The area between the arc and the tangents.
4 | Center point of the arc | The center point of the arc.
5 | Point of curvature (PC) | The start of the arc.
6 | Point of Intersection (PI) | The point at which the tangents intersect.
7 | Point of tangency (PT) | The end of the arc.
8 | Radius | The radius of the arc.
9 | Tangent | The distance from the PC or PT to the PI.
10 | Delta angle | The delta angle.
11 | Deflection angle | The deflection angle.
12 | Degree arc | The deflection angle that results in an arc length of 100 units.
13 | Degree chord | The deflection angle that results in a chord length of 100 units.
14 | Chord length | The chord length.
15 | Mid ordinate | The distance between the arc and the chord at the mid point of the arc.
16 | External | The minimum distance between the PI and the arc.
17 | Arc length | The arc length.

To compute points on the arc

1. Tap Layout to compute points on the arc at any station along the arc.

2. Select one of the methods in the Layout method field.

   PC deflection method

   Provides the deflection angle and distance to each specified station on the arc as if you are occupying the PC point and backsighting the PI point.

   Tap Calc to view the computed arc with these additional details:

   - Station – is the specified station along the arc.
   - Deflection – is the deflection angle from the tangent line (PC point to PI point) to the current station point on the arc.
   - Chord – is the distance to the current station point on the arc from the PC point.

   - Previous station – is the previously specified PC deflection station.

     This is available only if the immediately previous point was computed using the PC deflection method.

   - Short chord – is the chord distance from the current PC deflection point on the arc to the previous PC deflection point on the arc.

     This is available only if the immediately previous point was computed using the PC deflection method.

   1

   Point of curvature (PC)

   2

   Point of Intersection (PI)

   3

   Point of tangency (PT)

   4

   Center point of the arc

   5

   Current station

   6

   Chord

   7

   Deflection angle

   PI deflection method

   Provides the deflection angle and distance to each specified station on the arc as if you are occupying the PI point and backsighting the PC point.

   Tap Calc to view the computed arc with these additional details:

   - Station – is the specified station along the arc.
   - Deflection – the deflection angle from the incoming tangent line to the current station point on the arc.
   - PI to station – the distance to the current station point on the arc from the PI point.

   1

   Point of curvature (PC)

   2

   Point of Intersection (PI)

   3

   Point of tangency (PT)

   4

   Center point of the arc

   5

   Current station

   6

   PI to station

   7

   Deflection angle

   Tangent offset method

   Provides the perpendicular offset information from the tangent line (the line from the PC point to the PI point) to each specified station on the arc.

   Tap Calc to view the computed arc with these additional details:

   - Station – is the specified station along the arc.
   - Tangent dist (TD) – is the distance along the tangent line from the PC point toward the PI point where the perpendicular offset to the arc point occurs.
   - Tangent offset – is the perpendicular offset distance from the tangent line to the current station point on the arc.
   - Tangent – is the length of the tangent line (the distance from the PC point to the PI point).
   - Tangent – TD – is the remainder distance along the tangent line (the distance from the point of the perpendicular offset to the PI point).

   1

   Point of curvature (PC)

   2

   Point of Intersection (PI)

   3

   Point of tangency (PT)

   4

   Center point of the arc

   5

   Current station

   6

   Tan offset

   7

   Tan distance (TD)

   8

   Tangent – TD

   9

   Tangent

   Chord offset method

   Provides the perpendicular offset information from the long chord (the line from the PC point to the PT point) to each specified station on the arc. The PC deflection information is also provided.

   Tap Calc to view the computed arc with these additional details:

   - Station – is the specified station along the arc.
   - Chord dist – is the distance along the long chord from the PC point (toward the PT point) where the perpendicular offset to the arc point occurs.
   - Chord offset – is the perpendicular offset distance from the long chord to the current station point on the arc.
   - PC deflection – is the deflection angle from the tangent line (PC point to PI point) to the current station point on the arc.
   - Chord length – is the distance to the current station point on the arc from the PC point.

   1

   Point of curvature (PC)

   2

   Point of Intersection (PI)

   3

   Point of tangency (PT)

   4

   Center point of the arc

   5

   Current station

   6

   Chord distance

   7

   Chord offset

   8

   Chord length

   9

   PC deflection

3. To save the results to the job, tap Store.

To hide the Layout fields from the screen, tap Arc.

To add the arc and the points defining the arc to the job

1. Tap Add.
2. Select the start point for the arc, back tangent, and the back tangent direction.
3. Tap Calc.

4. Tap Store.

   The following information is added to the job:

   - calculated arc
   - point defining the end point of the arc
   - point defining the center point of the arc