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maths
Former Member
Posts: 1,876,323 The Mix Honorary Guru
Is there a whizz kid that can explain to me the context between:
sin(A+B) = sinA*cosB + cosA*sinB ???
I just don't get it. I browsed various webpages, but I couldn't follow the explanation.
Can someone explain it in a easy-to-follow fashion?
Thanks in advance.
sin(A+B) = sinA*cosB + cosA*sinB ???
I just don't get it. I browsed various webpages, but I couldn't follow the explanation.
Can someone explain it in a easy-to-follow fashion?
Thanks in advance.
Post edited by JustV on
0
Comments
It basically shows how you get from sin (A+B) to sinAcosB + cosAsinB.
Oh yes, please do...
This reminds me of the times I gave private lessons in physics over ICQ and drew a lot of MS Paints about the concepts of motors and generators
and other different stuff. I got the still saved here
I was amazing
"whoa, dude... Where do you get all the pictures from?"
"I draw them, while we speak."
"Wow..."
Thanks in advance, dude.
This is how ive got it in my notes:
Sin A = TS/OT
Sin B = PT/OP
Cos A = PQ/PT
Cos B = OT/OP
Right Now the proof.
Sin(A+B) = (PR)/(OP)
Sin(A+B) = (PQ + QR)/(OP)
Sin(A+B) = (PQ + TS)/(OP)
Sin(A+B) = (PQ/OP)+(TS/OP)
Sin(A+B) = (PQ/PT)*(PT/OP)+(TS/OT)*(OT/OP)
this gives:
Sin(A+B) = cosA sinB + sinA cosB
Any questions?
Yeah, I kinda am able to follow it.
thanks.
In fact its fairly essential to understand it.
Besides I think I did quite well for 10 minutes work in paint.
I don't get that one.
This is the cosinus of the very little triangle PQT.
not the one of A...
The other things are coherent, but this...
/e:
Yeah, I got it now... but it's pretty complicated. I won't be able to reconstruct that in maths, when I am called to the blackboard
I needed to calculate a "x" WITHOUT calculator so that
arcsin x = arcsin 1/3 + arcsin 4/5.
I conclude
sin(arcsin 1/3 + arcsin 4/5) = x
So I need this formula here for sin(A+B), where A is arcsin 1/3, and B is arcsin 4/5.
We didnot do it in the lectures, and I couldn't find it in our formula book.
I just tell him I found the answer in the endless abyss of the data superhighway the Interbutt, and he's going to accept it.
Ah I see its a small thing Known as Z angles. Basically angle S O T is the same as angle O T Q which is the same as angle T P Q. So you can say that Cos A is PQ/PT