Question #5df8b Trigonometry Trigonometric Identities and Equations Proving Identities 1 Answer P dilip_k Dec 21, 2016 GIVEN # tan(A+B)/tan(A-B) = lamda# # =>(sin(A+B)cos(A-B))/(sin(A-B)cos(A+B)) = lamda# By dividendo and componendo # =>((sin(A+B)cos(A-B))-(sin(A-B)cos(A+B)))/((sin(A+B)cos(A-B))+(sin(A-B)cos(A+B))) = (lamda-1)/(lambda+1)# #=>(sin(A+B-A+B))/(sin(A+B+A-B))=(lambda-1)/(lambda+1)# #=>(sin(2B))/(sin(2A))=(lambda-1)/(lambda+1)# Proved Answer link Related questions What does it mean to prove a trigonometric identity? How do you prove #\csc \theta \times \tan \theta = \sec \theta#? How do you prove #(1-\cos^2 x)(1+\cot^2 x) = 1#? How do you show that #2 \sin x \cos x = \sin 2x#? is true for #(5pi)/6#? How do you prove that #sec xcot x = csc x#? How do you prove that #cos 2x(1 + tan 2x) = 1#? How do you prove that #(2sinx)/[secx(cos4x-sin4x)]=tan2x#? How do you verify the identity: #-cotx =(sin3x+sinx)/(cos3x-cosx)#? How do you prove that #(tanx+cosx)/(1+sinx)=secx#? How do you prove the identity #(sinx - cosx)/(sinx + cosx) = (2sin^2x-1)/(1+2sinxcosx)#? See all questions in Proving Identities Impact of this question 2168 views around the world You can reuse this answer Creative Commons License