Without using a calculator, compute the sine and cosine of (7π) /4 by using the reference angle.

Question

Without using a calculator, compute the sine and cosine of ( by using the reference angle.

What is the reference angle? ____ radians

In what quadrant is this angle? ___

sin (7π) /4 =

cos (7π) /4 =

Answer 1

I don't know the terminology for sure, but I would guess the reference angle is π/4 which has sin=cos=sqrt(2)/2.

7π/4 is in quadrant 4 where the sin is negative and the cos is positive.