Question

Pls help, don’t quite understand these at all and need the correct answers:)

Answer 1

9514 1404 393

Answer:

  cos(A) ≈ 0.9165

Step-by-step explanation:

Put the given value into the given relation and solve for the unknown.

  sin²(A) +cos²(A) = 1

  (2/5)² + cos²(A) = 1

  cos²(A) = 1 -4/25 = 21/25 . . . . . subtract (2/5)²

  cos(A) = √(21/25) ≈ 0.9165 . . . . . take the square root

_____

Both sine and cosine are positive in Quadrant I, so we're only interested in the positive square root.