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 one year ago
Find an exact value.
cos 15°
Options:
A) sqrt 6 + sqrt 2 / 4
B)  sqrt2 + sqrt 6 / 4
C)  sqrt2  sqrt 6 / 4
D)  sqrt6 + 1 / 4
 one year ago
Find an exact value. cos 15° Options: A) sqrt 6 + sqrt 2 / 4 B)  sqrt2 + sqrt 6 / 4 C)  sqrt2  sqrt 6 / 4 D)  sqrt6 + 1 / 4

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Butterfly16
 one year ago
Best ResponseYou've already chosen the best response.0A) \[ \frac{ \sqrt{6}+\sqrt{2} }{ 4 } \] B) \[\frac{ \sqrt{2} +\sqrt{6} }{ 4 }\] C) \[\frac{ \sqrt{2}  \sqrt{6} }{ 4 }\] D) \[\frac{ \sqrt{6} +1}{ 4 }\]

amoodarya
 one year ago
Best ResponseYou've already chosen the best response.2cos(ab)=cosa cosb + sina sin b you know? if ok cos (4530)= cos45 cos 30 +sin 45 sin 30

Butterfly16
 one year ago
Best ResponseYou've already chosen the best response.0where did you get all the numebrs?

amoodarya
 one year ago
Best ResponseYou've already chosen the best response.2dw:1357845575004:dw I dont get what you mean !

Butterfly16
 one year ago
Best ResponseYou've already chosen the best response.0But its for cos 15° ?

amoodarya
 one year ago
Best ResponseYou've already chosen the best response.2It is an unknown angle you have to make it bu known angle

amoodarya
 one year ago
Best ResponseYou've already chosen the best response.2you know that formula? if yeah put the numbers in it you will have answer (a)

Butterfly16
 one year ago
Best ResponseYou've already chosen the best response.0I think I got it. Can you help with another?

klimenkov
 one year ago
Best ResponseYou've already chosen the best response.0Also, you can use \(\cos^2\frac x 2=\frac{1+\cos x}2\).

Butterfly16
 one year ago
Best ResponseYou've already chosen the best response.0@klimenkov Can you help with this one, pelase? Write the expression as either the sine, cosine, or tangent of a single angle. \[\cos(\frac{ \pi }{ 5 }) \cos(\frac{ \pi }{ 7 }) + \sin (\frac{ \pi }{ 5}) \sin (\frac{ \pi }{ 7 })\]

amoodarya
 one year ago
Best ResponseYou've already chosen the best response.2as "klimenkov " says you can use that formula shuch the way i drawdw:1357846727839:dw

amoodarya
 one year ago
Best ResponseYou've already chosen the best response.2cos(π/5)cos(π/7)+sin(π/5)sin(π/7)=cos (π/5π/7) by the formula AS i sayd before cos (a+b)= cos a cos bsin a sin b

Butterfly16
 one year ago
Best ResponseYou've already chosen the best response.0so would the cos (a+b) be pi/5+pi/7?

klimenkov
 one year ago
Best ResponseYou've already chosen the best response.0No. It will be \(\cos(\frac\pi5\frac\pi7)\) as @amoodarya said. Hope you can do this subtraction.

amoodarya
 one year ago
Best ResponseYou've already chosen the best response.2no i think that you get it cos (a+b)= cos a cos bsin a sin b cos (ab)= cos a cos b+sin a sin b but 2pi/35 is unknown angle

Butterfly16
 one year ago
Best ResponseYou've already chosen the best response.0\[\cos(\frac{ \pi }{ 5 }+\frac{ \pi }{ 7 })\] is 2pi/35? Can you show me how to fill in the formula? I think it'd make it easier for me.

amoodarya
 one year ago
Best ResponseYou've already chosen the best response.2cos (ab)= cos a cos b+sin a sin b a=pi/5 b=pi/7

Butterfly16
 one year ago
Best ResponseYou've already chosen the best response.0cos (pi/5pi/7)= cos (pi/5) cos (pi/7)+sin (pi/5) sin (pi/7) ?

Butterfly16
 one year ago
Best ResponseYou've already chosen the best response.0So the answers 2pi/35?

klimenkov
 one year ago
Best ResponseYou've already chosen the best response.0No. The answer is \(\cos(\frac{2\pi}{35})\).

Butterfly16
 one year ago
Best ResponseYou've already chosen the best response.0That's what I said?

klimenkov
 one year ago
Best ResponseYou've already chosen the best response.0You said this without cosine.
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