Question

find delta f using linear approximation when f(x)=cos (x) a=pi/4 and delta x= .04

Answer 1

linear approx usually deal with derivatives

Answer 2

yes the derivative of cos is -sin for the derivative of that i got -radical(2)/2

Answer 3

now im not sure what to do

Answer 4

right, thats the slope of the line at a,f(a)

Answer 5

y-f(a) = f'(a) (x-a)

Answer 6

how do i find delta f?

Answer 7

by using the equation of the tangent line at the given point; and checking that value for the change from a to a+h