Question

At what values of x does cos have a horizontal tangent line?

A) x=π/4 and x=3π/4
B) x=π/2 and x=3π/2
C) x=π and x=2π
D) x=0 and x=π

Answer 1

The values of x at which cos has a horizontal tangent line are x = π/2 and x = 3π/2.

Step-by-step explanation:

The values of x at which cos has a horizontal tangent line are x = π/2 and x = 3π/2.

To find these values, we need to determine the values of x for which the derivative of cos(x) equals 0. The derivative of cos(x) is -sin(x), so -sin(x) = 0. Since sin(x) = 0 when x = π/2 and x = 3π/2, these are the values where cos has a horizontal tangent line.