Question

If y=|cos x| then f'(3pi/4) is?

Answer 1

\[\frac{-1}{\sqrt{2}}\]

Answer 2

it should be +ve 1/root2

Answer 3

no, i don't think

Answer 4

the slope of the tangent is negative at the reqd point in the graph of f(x)=|cosx|

Answer 5

sorry, its 1/rt(2). u r right.

Answer 6

ok how did you get it

Answer 7

in the interval (pi/2,pi) the function is f(x)=+cosx
so its derivative is sinx and at 3pi/4 its value is 1/rt(2).
Observe that i had to find the sign of the function in the neighbourhood of the given point.

Answer 8

f(x)=-cos x in the intervl pi/2 to pi

Answer 9

yes...
so the value is positive.

Answer 10

i mean when u plug pi/2 in f(x), f(x) comes positive

Answer 11

f(x)=-cosx in pi/2 to pi
derivative of cosx is -sinx
so f'(x)=sinx

Answer 12

ok..got it

Answer 13

bingo