# Find an equation of the line tangent

## Homework Statement

f(x) = |sinx| for - π ≤ x ≤ π
g(x) = x^2
h(x)= g(f(x))

1. Find domain and range of h(x)
2. Find an equation of the line tangent to the graph of h at the point where x= π/4

## The Attempt at a Solution

It think that h(x) is (|sin x|)^2

so, is domain - π ≤ x ≤ π

here is where I am confused:

if d/dx (sin x) = cos x

then

is d/dx (|sin x|)^2 = (|cos x|)^2 ?

thanks in advance for the help.

danago
Gold Member
here is where I am confused:

if d/dx (sin x) = cos x

then

is d/dx (|sin x|)^2 = (|cos x|)^2 ?

thanks in advance for the help.

You cant do that. You should consider using the chain rule.

You cant do that. You should consider using the chain rule.

is there any rule for the derivate for an absolute value?

Dick
|x|= x if $x\ge 0$, -x is x< 0. Its derivative is 1 if x> 0, -1 if x< 0, not defined for x=0.