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kaylala
Group Title
TOPIC: Trigonometry
GIVEN THE FOLLOWING CONDITIONS:
sin A = 4/5, A Σ I
sin B = 3/5, B Σ III
Find the value of:
I. sin (A + B)
II. cos (A + B)
III. tan (A + B)
 7 months ago
 7 months ago
kaylala Group Title
TOPIC: Trigonometry GIVEN THE FOLLOWING CONDITIONS: sin A = 4/5, A Σ I sin B = 3/5, B Σ III Find the value of: I. sin (A + B) II. cos (A + B) III. tan (A + B)
 7 months ago
 7 months ago

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kaylala Group TitleBest ResponseYou've already chosen the best response.0
@eliassaab
 7 months ago

eliassaab Group TitleBest ResponseYou've already chosen the best response.1
I do not understand what comes after 4/5 and 3/5
 7 months ago

kaylala Group TitleBest ResponseYou've already chosen the best response.0
let me fix the question
 7 months ago

eliassaab Group TitleBest ResponseYou've already chosen the best response.1
Also look at this summary of trig formulas, your problem follows easily http://www.math.missouri.edu/escgi/mucgibin/trigidentities.cgi
 7 months ago

eliassaab Group TitleBest ResponseYou've already chosen the best response.1
It is still not fixed
 7 months ago

kaylala Group TitleBest ResponseYou've already chosen the best response.0
it is. see this pic that i will post. it's where i got the question. wait
 7 months ago

eliassaab Group TitleBest ResponseYou've already chosen the best response.1
You need these formulae sin(a + b ) = sin(a) cos(b) + sin(b) cos(a) sin(a  b ) = sin(a) cos(b)  sin(b) cos(a) cos(a + b ) = cos(a) cos(b)  sin(a) sin(b) cos(a  b ) = cos(a) cos(b) + sin(a) sin(b)
 7 months ago

kaylala Group TitleBest ResponseYou've already chosen the best response.0
oh it's (+_) the plus on top of the minus for I  III
 7 months ago

eliassaab Group TitleBest ResponseYou've already chosen the best response.1
You do first + than 
 7 months ago

eliassaab Group TitleBest ResponseYou've already chosen the best response.1
You need six answers
 7 months ago

eliassaab Group TitleBest ResponseYou've already chosen the best response.1
Where is the picture?
 7 months ago

kaylala Group TitleBest ResponseYou've already chosen the best response.0
wait. i just took a picture of it
 7 months ago

Yttrium Group TitleBest ResponseYou've already chosen the best response.2
@eliassaab , I think the information beside 4/5 and 3/5 are the position of angle in the cartesian plane. (specifically Quadrant I for <A and Quadrant III for <B
 7 months ago

kaylala Group TitleBest ResponseYou've already chosen the best response.0
@eliassaab here's the picture
 7 months ago

kaylala Group TitleBest ResponseYou've already chosen the best response.0
and yes those are values for the carthesian plane @Yttrium
 7 months ago

kaylala Group TitleBest ResponseYou've already chosen the best response.0
i dont think i have to find 6 answers @eliassaab
 7 months ago

kaylala Group TitleBest ResponseYou've already chosen the best response.0
somebody. anyone. please help
 7 months ago

Yttrium Group TitleBest ResponseYou've already chosen the best response.2
You really have to find 6 ansers @kaylala. Let me tell you this: \[\sin (A \pm B)\] is the notation for\[\sin (A+B)\] and \[\sin(AB)\] I hope you understand now.
 7 months ago

kaylala Group TitleBest ResponseYou've already chosen the best response.0
oh okay i see now @Yttrium
 7 months ago

kaylala Group TitleBest ResponseYou've already chosen the best response.0
i just dont know how to start this
 7 months ago

Yttrium Group TitleBest ResponseYou've already chosen the best response.2
let's start with angle A
 7 months ago

Yttrium Group TitleBest ResponseYou've already chosen the best response.2
the condition says sinA = 4/5, where it is in quadrant 1. we know that sinx = opp/hyp Hence, the figure much look like this. dw:1391508636187:dw
 7 months ago

Yttrium Group TitleBest ResponseYou've already chosen the best response.2
dw:1391508787128:dw let's say that adjacent side of A is x. Can you solve x now?
 7 months ago

kaylala Group TitleBest ResponseYou've already chosen the best response.0
okay x=sqrt9 ??? @Yttrium
 7 months ago

Yttrium Group TitleBest ResponseYou've already chosen the best response.2
isn't is sqrt(+9)? which is 3?
 7 months ago

kaylala Group TitleBest ResponseYou've already chosen the best response.0
it do is 3
 7 months ago

Yttrium Group TitleBest ResponseYou've already chosen the best response.2
Yea it is. And, with that you can now actually solve for cosA, tanA.
 7 months ago

kaylala Group TitleBest ResponseYou've already chosen the best response.0
i really dont know how to do this please guide me @Yttrium
 7 months ago

Yttrium Group TitleBest ResponseYou've already chosen the best response.2
cosA = adj/hyp tanA = opp/adj did you forget that?
 7 months ago

kaylala Group TitleBest ResponseYou've already chosen the best response.0
cos A = 3/5 ???
 7 months ago

kaylala Group TitleBest ResponseYou've already chosen the best response.0
did i get it?
 7 months ago

kaylala Group TitleBest ResponseYou've already chosen the best response.0
what do i do next?
 7 months ago

Yttrium Group TitleBest ResponseYou've already chosen the best response.2
You got this. I think it is better if you write sinA, cosA, and tanA in a piece of paper. They are really important later. Next thing we are going to do is to solve for cosB and tanB
 7 months ago

kaylala Group TitleBest ResponseYou've already chosen the best response.0
yeah. just wrote it down already how do i solve for that?
 7 months ago

kaylala Group TitleBest ResponseYou've already chosen the best response.0
? @Yttrium
 7 months ago

Yttrium Group TitleBest ResponseYou've already chosen the best response.2
you sure? isn't it 4? take note it is in the quadrant III.
 7 months ago

kaylala Group TitleBest ResponseYou've already chosen the best response.0
okay so the quadrant determines the sign? right?
 7 months ago

Yttrium Group TitleBest ResponseYou've already chosen the best response.2
Yeah. for (x,y) quadrant I (+,+) II (,+) III (,) IV (+,) Now. Find cosB and tanB. Be careful with the signs.
 7 months ago

Yttrium Group TitleBest ResponseYou've already chosen the best response.2
Solve for cosB and tanB
 7 months ago

kaylala Group TitleBest ResponseYou've already chosen the best response.0
cos B= 4/5
 7 months ago

kaylala Group TitleBest ResponseYou've already chosen the best response.0
tanB= 3/4
 7 months ago

Yttrium Group TitleBest ResponseYou've already chosen the best response.2
Ohhh wait!!!
 7 months ago

kaylala Group TitleBest ResponseYou've already chosen the best response.0
did i get it?
 7 months ago

Yttrium Group TitleBest ResponseYou've already chosen the best response.2
the graph will be like this dw:1391510194742:dw
 7 months ago

Yttrium Group TitleBest ResponseYou've already chosen the best response.2
x then is 4 solve again for cosB and tanB
 7 months ago

kaylala Group TitleBest ResponseYou've already chosen the best response.0
i see now but the answer for cos b and tan B still remains?
 7 months ago

kaylala Group TitleBest ResponseYou've already chosen the best response.0
so are those the answers already?
 7 months ago

kaylala Group TitleBest ResponseYou've already chosen the best response.0
what to do next?
 7 months ago

Yttrium Group TitleBest ResponseYou've already chosen the best response.2
ooops tanB = 3/4 = 3/4
 7 months ago

kaylala Group TitleBest ResponseYou've already chosen the best response.0
oh you're right
 7 months ago

Yttrium Group TitleBest ResponseYou've already chosen the best response.2
Now is the time to evaluate them. I. sin (A + B) = sinAcosB + cosAsinB II. cos (A + B) = cosAcos + sinAsinB
 7 months ago

Yttrium Group TitleBest ResponseYou've already chosen the best response.2
III. \[\tan(A \pm B) = \frac{ tanA \pm tanB }{ 1\mp tanAtanB }\]
 7 months ago

kaylala Group TitleBest ResponseYou've already chosen the best response.0
how's that? do i just substitute what i got? to the given formulas?
 7 months ago

Yttrium Group TitleBest ResponseYou've already chosen the best response.2
Yeah. All the operation found upside are the only operations used when applying upside identities. Look at this. \[\tan(A +B) = \frac{ tanA + tanB }{ 1  tanAtanB }\]
 7 months ago

kaylala Group TitleBest ResponseYou've already chosen the best response.0
so sin(a+b) = 1 sin(ab) = 7/25 ??? @Yttrium
 7 months ago

kaylala Group TitleBest ResponseYou've already chosen the best response.0
cos (a+b)=0 cos (ab)=24/25 did i get it correctly @Yttrium ?
 7 months ago

Yttrium Group TitleBest ResponseYou've already chosen the best response.2
i'll just check the sin function, you take care of the others :D sin(a+b) = 1
 7 months ago

kaylala Group TitleBest ResponseYou've already chosen the best response.0
okay :) thanks
 7 months ago

kaylala Group TitleBest ResponseYou've already chosen the best response.0
tan (A+B)= undefined??? is it? please check this @Yttrium
 7 months ago

Yttrium Group TitleBest ResponseYou've already chosen the best response.2
what is tanA and tanbB?
 7 months ago

kaylala Group TitleBest ResponseYou've already chosen the best response.0
tanA=4/3 tanB=3/4
 7 months ago

Yttrium Group TitleBest ResponseYou've already chosen the best response.2
Yeah. That's undefined. And that is normal. :))
 7 months ago

kaylala Group TitleBest ResponseYou've already chosen the best response.0
i see. okay thanks again :)
 7 months ago

Yttrium Group TitleBest ResponseYou've already chosen the best response.2
No problem :))
 7 months ago
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