## proof identity

Can someone help me to proof this identity

$(\vec{a} \times \vec{b})^2(\vec{a} \times \vec{b})^2-[(\vec{a} \times \vec{b})(\vec{a} \times \vec{b})]^2=[(\vec{a} \times \vec{b})\vec{c}]^2 \vec{a}^2$