Bruce T. answered • 09/22/18
Tutor
5.0
(165)
Mathematician for Algebra2 ,Precalculus, Trig. I HAVE YOUR BACK!!
The answer comes directly from the unit circle. 3pi/4=135 degrees or 90+45. Therefore the cos in quadrant 2 is negative. answer=-sqrt2/2
If I can help you further, please let me know!
Bruce
