If sin (a + π / 4) = 1 / 3, then cos (π / 4 + a) is equal to

If sin (a + π / 4) = 1 / 3, then cos (π / 4 + a) is equal to

sin（a+π/4）=1/3
Using Sin & # 178; (a + π / 4) + cos & # 178; (a + π / 4) = 1
The results show that cos & # 178; (a + π / 4) = 8 / 9
cos(a+π/4)=±2√2/3
∴
cos（π/4+a）=±2√2/3

What degree of COS is 4 / 5? What degree of COS is 3 / 5?

. cosx + SiNx = 7 / 5 find X. let's see sin & # 178; X + cos & # 178; X = 1, you know. According to the question, suppose Sin & # 178; X + cos & # 178; X + 2sinxcosx = 49 / 25  2sinxcosx = 24 / 25, then SiNx & # 178; + cos & # 178; x-2sinxcosx = 1-24 / 25 = 1 / 25  SiNx cosx = ± 1 / 51. Sinx-c

What degree of COS is equal to 0?

nπ+π÷2