CosA=1/under root2, SinA= -1/under root 2.?

find the value of A. thanks

1 Answer

Relevance
  • JOHN
    Lv 7
    7 years ago
    Favourite answer

    A is in the 4th quadrant from the info given. So A=7π/4. Verify: sin(7π/4)=sin (2π-π/4)=sin2πcosπ/4-cos2πsinπ/4=

    -sinπ/4=

    -1/√2, cos(7π/4)=cos(2π-π/4)=

    cos2πcosπ/4+sin2πsinπ/4=cosπ/4=1/√2.

Still have questions? Get answers by asking now.