Got Homework?
Connect with other students for help. It's a free community.
Here's the question you clicked on:
 0 viewing
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)
 8 months ago
 8 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)
 8 months ago
 8 months ago

This Question is Closed

kaylala Group TitleBest ResponseYou've already chosen the best response.0
@eliassaab
 8 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
 8 months ago

kaylala Group TitleBest ResponseYou've already chosen the best response.0
let me fix the question
 8 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
 8 months ago

eliassaab Group TitleBest ResponseYou've already chosen the best response.1
It is still not fixed
 8 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
 8 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)
 8 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
 8 months ago

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

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

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

kaylala Group TitleBest ResponseYou've already chosen the best response.0
wait. i just took a picture of it
 8 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
 8 months ago

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

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

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

kaylala Group TitleBest ResponseYou've already chosen the best response.0
somebody. anyone. please help
 8 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.
 8 months ago

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

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

Yttrium Group TitleBest ResponseYou've already chosen the best response.2
let's start with angle A
 8 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
 8 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?
 8 months ago

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

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

kaylala Group TitleBest ResponseYou've already chosen the best response.0
it do is 3
 8 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.
 8 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
 8 months ago

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

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

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

kaylala Group TitleBest ResponseYou've already chosen the best response.0
what do i do next?
 8 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
 8 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?
 8 months ago

kaylala Group TitleBest ResponseYou've already chosen the best response.0
? @Yttrium
 8 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.
 8 months ago

kaylala Group TitleBest ResponseYou've already chosen the best response.0
okay so the quadrant determines the sign? right?
 8 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.
 8 months ago

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

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

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

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

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

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

Yttrium Group TitleBest ResponseYou've already chosen the best response.2
x then is 4 solve again for cosB and tanB
 8 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?
 8 months ago

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

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

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

kaylala Group TitleBest ResponseYou've already chosen the best response.0
oh you're right
 8 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
 8 months ago

Yttrium Group TitleBest ResponseYou've already chosen the best response.2
III. \[\tan(A \pm B) = \frac{ tanA \pm tanB }{ 1\mp tanAtanB }\]
 8 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?
 8 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. \[\tan(A +B) = \frac{ tanA + tanB }{ 1  tanAtanB }\]
 8 months ago

kaylala Group TitleBest ResponseYou've already chosen the best response.0
so sin(a+b) = 1 sin(ab) = 7/25 ??? @Yttrium
 8 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 ?
 8 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
 8 months ago

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

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

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

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

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

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

Yttrium Group TitleBest ResponseYou've already chosen the best response.2
No problem :))
 8 months ago
See more questions >>>
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.