Question

What is sin(13pi/4)? Explain your thinking.
I know the answer is sqrt 2/2 , i just want to make sure that it's right.

Answer 1

it's incorrect, but you're close

Answer 2

13pi/4 - 2pi = 13pi/4 - 8pi/4 = 5pi/4

sin(13pi/4) = sin(5pi/4) = ??

Answer 3

i got 4pi/4

Answer 4

unless i'm doing it wrong @jim_thompson5910

Answer 5

use this unit circle

http://etc.usf.edu/clipart/43200/43215/unit-circle7_43215_lg.gif

Answer 6

oh! its just negative @jim_thompson5910

Answer 7

_ sqrt 2/2.

Answer 8

yes, \[\Large \sin\left(\frac{5\pi}{4}\right) = -\frac{\sqrt{2}}{2}\]

Answer 9

yay!! Thank you so much!:) @jim_thompson5910

Answer 10

sure thing

Answer 11

You can always do the calculation keeping in mind that \[\pi = 180 \ degrees\]