di jawab ya.............

[tex]r = \sqrt{ {(9)}^{2} + {(7)}^{2} } \\ \sqrt{81 + 49} \\ = \sqrt{130} [/tex]
maka, cos kml =
[tex] \cos(kml) = \frac{km}{lm} \\ = \frac{9}{ \sqrt{130} } \\ = \frac{9 \sqrt{130} }{130} [/tex]