$${1 \over 2}\left( {\overrightarrow a - \overrightarrow b } \right) \bullet \left( {\overrightarrow a - \overrightarrow c } \right)$$

$${1 \over 2}\left| {\left( {\overrightarrow a - \overrightarrow b } \right) \times \left( {\overrightarrow a - \overrightarrow c } \right)} \right|$$

$${1 \over 2}\left| {\overrightarrow a \times \overrightarrow b \times \overrightarrow c } \right|$$

$${1 \over 2}\left( {\overrightarrow a \times \overrightarrow b } \right) \bullet \overrightarrow c $$

$$0$$

$${1 \over 6}$$

$${1 \over 3}$$

$$1$$

$$4$$ (or) $$1$$

$$4$$ only

$$1$$ only

Undefined

$$0$$

$$1$$

$$25$$

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