Formula : –

(iii)Three vectors a ⃗,b ⃗, and c ⃗are coplanar if and only if

Given: -

we know that three vector are coplanar if their scalar triple product is zero

we have

using

= 1(10 – 42) – 2(15 – 35) – 1(18 – 10)

= 0.

Hence, the Given vector are coplanar.