Trig using Sum and Difference Formulas

[bluewater]

here's the work i got so far. i guess what im trying to get help for this problem is the last few steps at the end
1. tan15 degrees
tan(A-B)=(tanA-tanB)/(1+tanAtanB)
tan(45-30)=(tan45-tan30)/(1+tan45tan30)
tan(45-30)=[1-(?3/3)]/[(1+1(?3/3)]
tan(45-30)=[1-(?3/3)]/[(1+1(?3/3)]*3
tan(45-30)=(3-?3)/(3+?3)


answer = 2 - ?3



completely stuck on this problem.
2. sin (17pi/12)




Thanks in advance.

 

[Deleted member 4993]

here's the work i got so far. i guess what im trying to get help for this problem is the last few steps at the end
1. tan15 degrees
tan(A-B)=(tanA-tanB)/(1+tanAtanB)
tan(45-30)=(tan45-tan30)/(1+tan45tan30)
tan(45-30)=[1-(?3/3)]/[(1+1(?3/3)]
tan(45-30)=[1-(?3/3)]/[(1+1(?3/3)]*3
tan(45-30)= (3-?3)/(3+?3) ................rationalize the denominator

tan 15° = [(3-?3)/(3+?3)] * [(3-?3)/(3-?3)] = (3-?3)[sup:c2b5njg8]2[/sup:c2b5njg8]/[3[sup:c2b5njg8]2[/sup:c2b5njg8] - (?3)[sup:c2b5njg8]2[/sup:c2b5njg8]] = (9 - 6?3 + 3)/(9 - 3)

Now continue...

answer = 2 - ?3



completely stuck on this problem.
2. sin (17pi/12) = sin(? + 5?/12) = - sin(5?/12) = - sin (?/4 + ?/6) ... Now continue ...




Thanks in advance.

 

[Chadmama]

HI guys

Power-reduction formulas. 8 Product-to- sum and sum-to-product can be shown by using either the sum and difference identities or the multiple-angle formulae.and simplifying the right hand side of each formula using the Angle Sum and Difference Theorem will produce the left hand side


Thanks

 

[Denis]

Power-reduction formulas. 8 Product-to- sum and sum-to-product can be shown by using either the sum and difference identities or the multiple-angle formulae.and simplifying the right hand side of each formula using the Angle Sum and Difference Theorem will produce the left hand side
Thanks

What is your point, mama?