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anonymous
 5 years ago
If sin(x) = 1/3 and sec(y) = 5/4 , where x and y lie between 0 and pie/2, evaluate the expression cos(x+y).
anonymous
 5 years ago
If sin(x) = 1/3 and sec(y) = 5/4 , where x and y lie between 0 and pie/2, evaluate the expression cos(x+y).

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myininaya
 5 years ago
Best ResponseYou've already chosen the best response.0sinx=1/3 secy=1/cosy=5/4 => cosy=4/5 cos(x+y)=cosxcosysinxsiny =cosx(4/5)(1/3)siny so now we need to know cosx and siny i drew two triangles one where sinx=1/3=20/(3*20) one where cosx=4/5=12*4/(12*5) i got the following conclusion: sin(y)=36/60=3/5 and cosx=40(2)^(1/2)/60=2(2)^(1/2)/3 so we have cos(x+y)=\[\frac{2\sqrt{2}}{3}*\frac{4}{5}\frac{1}{3}*\frac{3}{5}=\frac{8\sqrt{2}3}{15}\]

myininaya
 5 years ago
Best ResponseYou've already chosen the best response.0i think: i used the Pythagorean thm twice

myininaya
 5 years ago
Best ResponseYou've already chosen the best response.0im not sure i think i need to think more

myininaya
 5 years ago
Best ResponseYou've already chosen the best response.0ok right answer but this approach is retarded so here is a better approach

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0could you also answer another one for me?

myininaya
 5 years ago
Best ResponseYou've already chosen the best response.0im fixing to go to bed :(

myininaya
 5 years ago
Best ResponseYou've already chosen the best response.0make a new post im sure someone will help

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0\[\text{Cos}\left[\text{ArcSec}\left[\frac{5}{4}\right]+\text{ArcSin}\left[\frac{1}{3}\right]\right]=\frac{1}{5}+\frac{8 \sqrt{2}}{15} \]

myininaya
 5 years ago
Best ResponseYou've already chosen the best response.0yay! thanks rob that confirms what i did :) except a different way

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0Glad you were there first. Adios.

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0Thank you for the metals.

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0I think I ought to go to bed. Thanks for the "Medals"
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