Question

1.1 Find the value of 𝑐 for which the vectors (𝑐, 1, 1) and (−1, 2, 0) are orthogonal 

(perpendicular).

Answer 1

$$c(-1)+1(2)+1(0)=0$$

$$c=2$$

The vectors (2, 1, 1) and (−1, 2, 0) are orthogonal (perpendicular).