Question

How do I show that two given vectors are orthogonal

Answer 1

Two vectors are orthogonal when an angle between them is $\frac{\pi}{2}$ in radians

or 90 degrees. Then scalar production equals 0, because $\cos{\frac{\pi}{2}}=0.$

If we have two vectors $\overrightarrow{x}(x_1,x_2)$ and $\overrightarrow{y}(y_1,y_2)$ in Euclidean system

then $x_1*y_1+x_2*y_2=0.$