Approximate cos (12π/ 13) by using a linear approximation with f (x) = cos x.

First pick a value of close to . You should be fine with .

The linear approximation of at is given by



where is some fixed value close to . You have



so





The actual value is closer to -0.9709, so the approximation is decent.

Then why is the question on here if you know the answer

Absolute value graph shifted point 5 up