Question

Find the exact value by using a half-angle identity.

sine of seven pi divided by eight.

Answer 1

\[\frac{7\pi}{8}\] is half of \[\frac{7\pi}{6}\]

Answer 2

thats it?

Answer 3

@satellite73 7π/8 is NOT half of 7π/6

Answer 4

@jon321 do you know what the half of 7π/8 would be then?

Answer 5

1.37

Answer 6

lol so it isnt!

Answer 7

nope lol

Answer 8

multiply \(\frac{7\pi}{8}\) by \(2\)

Answer 9

and forget about decimals, you are supposed to use the "half angle" formula, like it says

Answer 10

.3827

Answer 11

7pie/4

Answer 12

yeah that one

Answer 13

thats the answer?

Answer 14

you'll need to know the value of cos(7pi/4) and you'll plug it into the half angle identity

see this reference sheet

http://tutorial.math.lamar.edu/pdf/Trig_Cheat_Sheet.pdf

specifically, the "Half Angle Formulas" section at the top of page 2