Question

Can someone please explain how to use the half-angle formula to solve sin Pi/8?

Answer 1

hi jake are yo there? do yo know the formula for half angle ?

Answer 2

sin(x/2)=sqrt((1-cosx)/2)

Answer 3

i think it is sin alpha/2=the square root of 1-cos alpha/2. it looks really weird having to type it out

Answer 4

so alpha is just x. that makes more sense

Answer 5

yes ..ok you can find x here by eqating x/2=pi/8

Answer 6

i got x=.7853...

Answer 7

ok use that for the right hand side

Answer 8

I'm sorry I don't know what the next step is..

Answer 9

ok here it is ill give you it more better

Answer 10

sin((pi/4*2)=sqrt(1-cos(pi/4)/2)
=sqrt((1-(sqrt2)/2))2
=sqrt((2-sqrt2))/4
=sqrt(.1464466)
=.38268

Answer 11

so pi/4 became your x here

Answer 12

does it make sense ?

Answer 13

yes that is making sense. i'm just trying to redo it on paper to see if i can get the same answer. Thank you very much

Answer 14

ok wc jake

Answer 15

you got it....good luck

Answer 16

Thanks!

Answer 17

k,yo have any more question or anymore prob i can help u maybe?

Answer 18

are you not busy?

Answer 19

not really lol

Answer 20

haha well i'm in pre cal obviously and not very good at it. i have this problem: if sin theta=3/5, and tan theta<0 then in what quadrant is the point (cos theta, sin theta)?

Answer 21

ok here we can put theta =x...therefore tanx=sinx/cosx
so x=3/5 its in the first quadrant..but tanx is negative)
so it is obvius that sin 3/5 is in the first quadrant and the cosx is in the 3rd quadrant

Answer 22

cos x in the third quadrant is negative sign

Answer 23

tanx <0 means tanx is a negatinve sign

Answer 24

Wow thank you for your help mark