Question

Show that four points whose position vectors are 6i - 7j, 16i - 19j - 4k, 3i - 6k, 2i - 5j + 10k are coplanar.

Answer 1

Formula:-

Let

The four points are coplanar if the vector \(\vec {AB},\vec {AD},\vec{AC}\) are coplanar.

now, using

= 10(100 + 12) + 12( – 60 – 24) – 4( – 12 + 40) = 0.

Hence the point are coplanar.