Length of a line or edge 
The line. 

Angle between two lines 
Two lines, or a line and a model edge. 
Placement of the dimension affects the way the angle is measured. Video: Dimensioning the Angle Between Two Lines

Distance between two lines 
Two parallel lines or a line and a parallel model edge. 

Perpendicular distance from a point to a line 
The point and the line or model edge. 

Distance between two points 
Two points. 
One of the points can be a model vertex.
These distance dimensions were all created by selecting the same two points, then selecting a different location for each dimension:
Video: Dimensioning PointtoPoint

Radius of an arc 
The arc. 

True length of an arc 
The arc, then the two end points. 
Video: Dimensioning Arc Length 
Diameter of a circle 
The circumference. 
Displayed as linear or diameter, depending on placement.
Video: Dimensioning a Circle

Distance when one or both entities is an arc or a circle 
The centerpoint or the circumference of the arc or circle, and the other entity (line, edge, point, etc.). 
By default, distance is measured to the centerpoint of the arc or circle, even when you select the circumference. 
Midpoint of a linear edge 
Rightclick the edge whose midpoint you want to dimension and click Select Midpoint. Then select the second entity to dimension. 
You can also dimension to midpoints when you add baseline or ordinate dimensions. 
The doubled distance between a sketch entity and centerline 
The sketch entity, then the centerline. Then drag the pointer to the opposite side of the centerline. 
Doubled distance relations create a value that is twice the distance of the sketch entity to the centerline. These relations help you determine the equal distance to the other side of the centerline. Doubled distance relations are helpful when you create profile sketches for revolved features.
Video: Dimensioning Doubled Distance
