Question

Calculate the modulus and unit vector of
1 r1=2i-5j+7k
2 r2=3i+8j-k

Answer 1

1) $|r_1|=\sqrt{2^2+(-5)^2+7^2}=\sqrt{78}.$

$u_1=\frac{2}{\sqrt{78}}i-\frac{5}{\sqrt{78}}j+\frac{7}{\sqrt{78}}k$

2) $|r_2|=\sqrt{3^2+8^2+(-1)^2}=\sqrt{74}$ .

$u_2=\frac{3}{\sqrt{74}}i+\frac{8}{\sqrt{74}}j-\frac{1}{\sqrt{74}}k$