how to find the equation of the tangent line?

Question

y = cos² x

when x = π/3

it also lets me know to use the radian measure

this is what i did so far:

y ' = -sin (2x)

= -sin (2 (π/3))

= -0.0365 is the slope

Answer 1

Use point-slope form from Algebra 1.

(y - cos² π/3) / (x - π/3) = -0.0365