Question

Can someone please help me understand this: Find the exact value by using a half-angle identity.

sin 7PI/8

Answer 1

http://www.purplemath.com/modules/idents.htm

Here is the half angle id. Just plug and go.

Answer 2

and your angle is 45 :P

Answer 3

@Catch.me how do you know it's 45

Answer 4

did you do 7pi/8 *(pi/180) ?

Answer 5

right
7 * 180 / 8 multiply it by 2 =7*180/4=315
and it is in the fourth quad ,so its cosine is the same as 45

Answer 6

Can I set it up like this: