i was the town hall this video clip and at 5:30 $cos fracpi2$ is substituted through $0$. Using my calculator the an outcome I gained was $-0.5$. I m sorry one is correct?


*

*

$cosleft(fracpi2 ight)=0$. The reason you are getting $-0.5$ is since you space not placing brackets roughly $pi/2$. Thus, you room obtaining the value of $(cospi)/2=(-1)/2=-0.5$. You have to use the brackets together follows: $cosleft(fracpi2 ight)$.


*

*

There room a couple ways to display that $cos (pi/2)=0$

1) The worth $ an(pi/2)$ is undefined. Due to the fact that $ an(x)=fracsin(x)cos(x)$, and also both $sin(x)$ and also $cos(x)$ are continuous throughout the reals, this implies that it have the right to only occur if $cos (pi/2)=0$.

You are watching: Cos(-pi/2)

2) The co-function identification $cos(pi/2-x)=sin(x)$ means that $cos (pi/2)=cos(pi/2-0)=sin(0)=0$

3) Looking in ~ the unit circle wherein $y=sin( heta)$ and $x=cos( heta)$. Once $ heta= 90^0=pi/2$, $sin ( heta)=1$ and $cos( heta)=0$.

4) the derivative the $sin(x)$ is $0$ only when $sin(x)=1$, which just occurs as soon as $x= fracnpi2$ for any type of $nin 4476mountvernon.combb N$. Because the derivative that $sin(x)$ is $cos(x)$ this indicates that $cos(pi/2)=cos((1)pi/2)=0$.

If you have any qustions permit me recognize below.


re-publishing
point out
follow
answer Mar 3 "17 in ~ 23:21
*

Sentinel135Sentinel135
61155 silver badges1111 bronze badges
$endgroup$
add a comment |

her Answer


Thanks for contributing solution to 4476mountvernon.comematics Stack Exchange!

Please be certain to answer the question. Carry out details and also share your research!

But avoid

Asking for help, clarification, or responding to other answers.Making statements based on opinion; back them increase with referrals or personal experience.

Use 4476mountvernon.comJax to style equations. 4476mountvernon.comJax reference.

To discover more, see our tips on writing an excellent answers.

See more: Watch What We Do In The Shadows Amazon Prime, Where To Watch It Online


Draft saved
Draft discarded

Sign increase or log in


sign up utilizing Google
sign up using Facebook
sign up utilizing Email and also Password
send

Post as a guest


name
email Required, but never shown


Post together a guest


surname
email

Required, but never shown


short article Your price Discard

By click “Post your Answer”, you agree come our terms of service, privacy policy and also cookie policy


Not the prize you're looking for? Browse various other questions tagged calculator or ask your own question.


Featured on Meta
connected
6
Base-2 exponentiation an insect on citizen SR-270X because that $2^255$?
2
an adverse × negative = Positive... Right?
2
Why walk this always equal $1$?
3
can I find the size of the side of a triangle without a calculator?
1
Calculators doing numeric integration
0
why go $sinleft(sin x + cos y ight)=cosleft(sinleft(xcdot y ight)+ cos x ight)$ look for this reason weird?
2
$|2sin^2 x-1|>cos x$: graphic and analytical technique resolution
0
confound calculator result
warm Network concerns much more hot inquiries

concern feed
i ordered it to RSS
concern feed To subscribe to this RSS feed, copy and paste this URL into your RSS reader.


4476mountvernon.com
agency
stack Exchange Network
site design / logo © 2021 stack Exchange Inc; user contributions licensed under cc by-sa. Rev2021.10.22.40552


4476mountvernon.comematics ridge Exchange works finest with JavaScript permitted
*

her privacy

By clicking “Accept every cookies”, friend agree ridge Exchange deserve to store cookie on your maker and disclose info in accordance with our Cookie Policy.