Question

Find the zeros of the function in the interval (-2 pie, 2 pie). f(x) = 3 cos x

Answer 1

Roots are -π/2 and π/2

Explanation:

`{ \bf{f(x) = 3 \cos(x) }}`

when x is -2π:

`{ \sf{f( - 2\pi) = 3 \cos( - 2\pi) }} \\ { \sf{ = 3}}`

hence -2π is not a zero of the function

when x is 2π:

`{ \sf{f(2\pi) = 3 \cos(2\pi) }} \\ { \sf{ = 3}}`

hence 2π is not a zero of the function

when x is π/2:

`{ \sf{f( (\pi)/(2)) = 3 \cos( (\pi)/(2) ) }} \\ { \sf{ = 0}}`

Hence ±π/2 is the zero of the function.