Johnny Bravo: Need help with a derivative

[Johnny Bravo]

Find the slope of the tangent line at the given point.

x=tan(y) The given point is y=pi/3

I keep getting 4 but the answer is 1/4. Could someone please explain the steps to get 1/4?

Thank you,
JB

[Don Schlesinger]

> Find the slope of the tangent line at the
> given point.

> x=tan(y) The given point is y=pi/3

> I keep getting 4 but the answer is 1/4.
> Could someone please explain the steps to
> get 1/4?

x = tan y ( Take the derivative of both sides of the equation implicitly)

1 = [(sec y)^2] X ( dy/dx )

dy/dx = 1/(sec y)^2 = (cos y )^2

Evaluated at y = pi/3,
(cos pi/3)^2 = (cos 60 )^2 =( 1/2 )^2 = 1/4

QED

Don

[Johnny Bravo]

[Hollywood]

> x = tan y ( Take the derivative of both
> sides of the equation implicitly)

> 1 = [(sec y)^2] X ( dy/dx )

> dy/dx = 1/(sec y)^2 = (cos y )^2

> Evaluated at y = pi/3,
> (cos pi/3)^2 = (cos 60 )^2 =( 1/2 )^2 = 1/4

> QED

> Don

When I see a post like this, i'm honored just to know you guys.

Hollywood