A community for students.
Here's the question you clicked on:
 0 viewing
pottersheep
 4 years ago
I really need help with this Trig identity please!(Grade 12!)
How do I prove that sinxsiny = 2cos([x+y]/2)sin([x+y]/2)
pottersheep
 4 years ago
I really need help with this Trig identity please!(Grade 12!) How do I prove that sinxsiny = 2cos([x+y]/2)sin([x+y]/2)

This Question is Closed

pottersheep
 4 years ago
Best ResponseYou've already chosen the best response.0I've been at it for so long! I cant get it :(

pottersheep
 4 years ago
Best ResponseYou've already chosen the best response.0We have only learnt compound angles, by the way

anonymous
 4 years ago
Best ResponseYou've already chosen the best response.0So there is an identity that's called co function identies, do you know them?

anonymous
 4 years ago
Best ResponseYou've already chosen the best response.0Or sum to product identities. Do any of these sound familiar.

pottersheep
 4 years ago
Best ResponseYou've already chosen the best response.0Is it the cos(90x) kind of thing?

anonymous
 4 years ago
Best ResponseYou've already chosen the best response.0um, not really. Here, let me post a link.

pottersheep
 4 years ago
Best ResponseYou've already chosen the best response.0Thanks Ill read it!

pottersheep
 4 years ago
Best ResponseYou've already chosen the best response.0nope....never learnt those :s

anonymous
 4 years ago
Best ResponseYou've already chosen the best response.0Give me like 510 minutes. This one is a little tricky. I'll try to keep you updated with the steps.

pottersheep
 4 years ago
Best ResponseYou've already chosen the best response.0Alright I really appreciate it

pottersheep
 4 years ago
Best ResponseYou've already chosen the best response.0I found a note that our teacher wrote on the board! I dont get it though... he wrote

pottersheep
 4 years ago
Best ResponseYou've already chosen the best response.0sinx + siny = sin(a+b) = sinacosB + cosAsinB sin(ab) = sinAcosB  cosAsinB sin(a+B) + sin (a  b) = 2sinAcosB

pottersheep
 4 years ago
Best ResponseYou've already chosen the best response.0ignore the caps they are the same letter

pottersheep
 4 years ago
Best ResponseYou've already chosen the best response.0Then he wrote : let : a+b = x a  b = y 2a = x+y x = (x+y)/2

anonymous
 4 years ago
Best ResponseYou've already chosen the best response.0Okay, Do you know the double angle formula?

anonymous
 4 years ago
Best ResponseYou've already chosen the best response.0okay, so cos([x+y]/2)sin([x+y]/2). This equal sin(x+y)

anonymous
 4 years ago
Best ResponseYou've already chosen the best response.0Are you following what i mean here?

anonymous
 4 years ago
Best ResponseYou've already chosen the best response.0how about this. 2cosAsinA=sin2a. A=(x+y)/2

anonymous
 4 years ago
Best ResponseYou've already chosen the best response.0cosine of x is sine of (90x) right?

anonymous
 4 years ago
Best ResponseYou've already chosen the best response.0okay. so =sin(x+y) =sinxcosy+sinycosx =sinx sin(90y)+siny sin(90x)

anonymous
 4 years ago
Best ResponseYou've already chosen the best response.0I have a quick question, is it sin(x+y)/2 or sin(xy)/2?

pottersheep
 4 years ago
Best ResponseYou've already chosen the best response.0one sec for the original question?

pottersheep
 4 years ago
Best ResponseYou've already chosen the best response.0oh no! you are right it sin(xy)!!!!!!!

anonymous
 4 years ago
Best ResponseYou've already chosen the best response.0Ok, that makes more sense now.

anonymous
 4 years ago
Best ResponseYou've already chosen the best response.0Give me another minute to type this up.

anonymous
 4 years ago
Best ResponseYou've already chosen the best response.0ok let me know if you can see it.

pottersheep
 4 years ago
Best ResponseYou've already chosen the best response.0I can see it! Im following through fine so far. Thank you so much
Ask your own question
Sign UpFind more explanations on OpenStudy
Your question is ready. Sign up for free to start getting answers.
spraguer
(Moderator)
5
→ View Detailed Profile
is replying to Can someone tell me what button the professor is hitting...
23
 Teamwork 19 Teammate
 Problem Solving 19 Hero
 Engagement 19 Mad Hatter
 You have blocked this person.
 ✔ You're a fan Checking fan status...
Thanks for being so helpful in mathematics. If you are getting quality help, make sure you spread the word about OpenStudy.