- #1

- 14

- 0

## Homework Statement

gradient of the stationary points of y=1-2sinx domain 0<x<2pi

## Homework Equations

## The Attempt at a Solution

dy/dx = -2cosx

-2cosx=0......?

Last edited:

You are using an out of date browser. It may not display this or other websites correctly.

You should upgrade or use an alternative browser.

You should upgrade or use an alternative browser.

- Thread starter pip_beard
- Start date

- #1

- 14

- 0

gradient of the stationary points of y=1-2sinx domain 0<x<2pi

dy/dx = -2cosx

-2cosx=0......?

Last edited:

- #2

rock.freak667

Homework Helper

- 6,223

- 31

- #3

- 14

- 0

Sorry. the qu reads 'the curve y=1-2sinx has domain 0<x<pi. find the gradients of the curve at the points where the curve crosses the x-axis

- #4

rock.freak667

Homework Helper

- 6,223

- 31

Sorry. the qu reads 'the curve y=1-2sinx has domain 0<x<pi. find the gradients of the curve at the points where the curve crosses the x-axis

Ah that is different.

Well you know the gradient function is dy/dx.

You need to find when the curve crosses the x-axis, or when y=0.

- #5

- 14

- 0

so do i differentiate it and make it = 0?

so i get -2cosx=0

so i get -2cosx=0

- #6

- 14

- 0

so do i differentiate it and make it = 0?

so i get -2cosx=0

how to i rearrange this to work it out?

- #7

rock.freak667

Homework Helper

- 6,223

- 31

so do i differentiate it and make it = 0?

so i get -2cosx=0

how to i rearrange this to work it out?

No if y=1-2sinx, the curve crosses, the x-axis when y=0

so solve 1-2sinx=0 for x. Can you do that?

- #8

- 14

- 0

-2sinx=1

sinx=-1/2

sinx=-1/2

- #9

rock.freak667

Homework Helper

- 6,223

- 31

-2sinx=1

sinx=-1/2

which gives x as ? ( in the given domain that is)

- #10

- 14

- 0

therfore value = 3.6651 and 6.2832?????

- #11

rock.freak667

Homework Helper

- 6,223

- 31

-2sinx=1

sinx=-1/2

therfore value = 3.6651 and 6.2832?????

this should be sinx=1/2.

But how did you get that value for x?

- #12

- 14

- 0

ohhh... did sin^-1... so ....

x principle = 0.479425

so pi - 0.4879425 = 2.66216

x principle = 0.479425

so pi - 0.4879425 = 2.66216

- #13

rock.freak667

Homework Helper

- 6,223

- 31

ohhh... did sin^-1... so ....

x principle = 0.479425

so pi - 0.4879425 = 2.66216

you should get x= π/6 and another one, best to use the exact values, I don't have a calculator with me to divide out pi.

- #14

- 14

- 0

ok. i'll have a play and post back if i cant do it.. Thanks for the inspiration!

Share: