In the Discussion of Kepler's Second Law of Planetary Motion $\frac { d A } { d t }$

Multiple Choice

In the discussion of Kepler's Second Law of Planetary Motion, the expression $\frac { d A } { d t }$ can be expressed as

A) $\frac { 1 } { 2 } \| \mathbf { r } ( t ) \times \mathbf { v } ( t ) \|$
B) $\| \mathbf { r } ( t ) \times \mathbf { v } ( t ) \|$
C) $\frac { 1 } { 2 } \| \mathbf { r } ( t ) \bullet \mathbf { v } ( t ) \|$
D) $\| \mathbf { r } ( t ) \bullet \mathbf { v } ( t ) \|$
E) $\mathbf { r } ( t ) \bullet \mathbf { v } ( t )$