+0  
 
0
161
3
avatar+223 

Im ripping my hair out with these stupid questions. How the heck do i find a cos A and cos B if only have sin A sin B?

From what i have here on my notes from my teacher, it shows different examples. If i had each of one i could do the the problem my just simply plugging it in the formula. So with these ones i tried to find them by doing this. I used this formula

 

cos ^ 2 = 1 - sin ^ 2        I would just plugin the both of the sin's? I know its wrong now that i need help, 

Veteran  Mar 18, 2017
Sort: 

2+0 Answers

 #1
avatar+26241 
0

Using cos2 = 1 - sin2 

 

cos2A = 1 - 5/25 = 20/25   so   cosA = 2√5/5

 

cos2B = 1 - 1/25 = 24/25   so   cosB = 2√6/5

 

cos(B-A) = cosBcosA + sinBsinA

 

sin(B-A) = sinBcosA - sinAcosB

 

Can you take it from here?

Alan  Mar 18, 2017
edited by Alan  Mar 19, 2017

16 Online Users

avatar
avatar
avatar
avatar
We use cookies to personalise content and ads, to provide social media features and to analyse our traffic. We also share information about your use of our site with our social media, advertising and analytics partners.  See details