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anonymous
 5 years ago
Can someone help me to prove this?
(cosA+cosB)/(cosAcosB)=cot((1/2)(AB))cot((1/2)(A+B))
anonymous
 5 years ago
Can someone help me to prove this? (cosA+cosB)/(cosAcosB)=cot((1/2)(AB))cot((1/2)(A+B))

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anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0we can use a few identities to rewrite the right hand side. First right it as product of two cosines over product of two sines. Then I used cos(u +/ v)= cos(u)cos(v) /+ sin(u)sin(v) sin(u +/ v)= sin(u)cos(v) +/ cos(u)sin(v) sin^2(x)=(1cos(2x))/2 cos^2(x)=(1+cos(2x))/2. its just a matter of running the algebra then. Let me know if you need help with any steps or getting started.

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0yeah I need help. Im really confused with this

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0Please can you show me the work?

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0Trying to learn trigonometry

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0ok the right hand side can be written... {cos((AB)/2)*cos((A+B)/2)}/{sin((AB)/2)*sin((A+B)/2)}

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0each term is in the form of the first 2 identities that i posted

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0so if you write them out and then multiply you'll get terms in the form of the 3rd and 4th identities I posted

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0It all simplifies down to the left hand side

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0let me check it out. I will write you if i get lost. Thanks

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0http://www.sosmath.com/trig/Trig5/trig5/trig5.html here are a bunch of identities

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0These trig problems are always mindless manipulation of symbols. I'll have a go at it and get back to you shortly.

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0OK. The sum and difference formulae for cosines are as follows: CosA + CosB = 2cos((A+B)/2)cos((AB)/2) and CosA  CosB = 2sin((A+B)/2)sin((aB)/2) So, your LHS = cot((A+B)/2)cot((AB)/2) Note. I have a minus sign in front of your solution.

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0i had a negative as well

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0yeah the solution has a  sign

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0emun i answered one of your old physics questions, when you were asking about dimensions you meant units right?

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0yeah. I dint know how to put that question into english. And your right, i ment units.

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0ok, I've heard units called dimensions before I was just making sure that's what you meant.

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0In spanish we say dimension. I supposed it was the same in English. lol
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