MATLAB: Making a transformation matrix and using it to rotate vectors

Question

Hi so i have little experience with MATLAB so I dont understand the syntax to use and cant find it basically I have to do this

So what i tried to do is this

format short
sym x
 
R(x)= [cos(x), -sin(x); cos(x), sin(x)]
x=pi/7
A=R(pi/7)

but I end up getting

A =
 
[ cos(pi/7), -sin(pi/7)]
[ cos(pi/7),  sin(pi/7)]

but I want that to be evaluated, what do I do?

Sorry if i sound uneducated with this, I have never used MATLAB before

Answer 1

No need to use symbolic here.

x = pi/7; 
A =[cos(x),-sin(x);cos(x),sin(x)]; 
v = [2;-7]; 
Answer = A*v;