Answer:
[tex]\theta\text{ = 115.67}\degree[/tex]Explanation:
Here, we want to find the angle between the two vectors
Mathematically, we have that as:
[tex]cos\text{ }\theta\text{ = }\frac{a.b}{|a||b|}[/tex]The denominator represents the magnitude of each of the given vectors as a product while the numerator represents the dot product of the two vectors
We have the calculation as follows:
[tex]\begin{gathered} cos\text{ }\theta\text{ = }\frac{(1\times8)+(-9\times5)}{\sqrt{1^2+(-9)\placeholder{⬚}^2}\text{ }\times\sqrt{8^2+5^2}} \\ \\ cos\text{ }\theta\text{ = }\frac{8-45}{\sqrt{82}\text{ }\times\sqrt{89}} \\ \\ \end{gathered}[/tex][tex]\begin{gathered} cos\text{ }\theta\text{ = }\frac{-37}{\sqrt{82}\text{ }\times\sqrt{89}} \\ cos\text{ }\theta\text{ = -0.4331} \\ \theta\text{ = }\cos^{-1}(-0.4331) \\ \theta\text{ = 115.67}\degree \end{gathered}[/tex]