Question

Which of the following correctly uses the special triangles on the unit circle to determine θ
in degrees when cosθ=2√2
? You may assume that 0°≤θ≤180°
.

(1 point)
Responses

30°

30 degrees

60°

60 degrees

90°

90 degrees

45°

Answer 1

cos θ = 2√2 has no solution (|cos θ| ≤ 1). If the intended value was √2/2 (the common special-triangle value), then θ = 45° (since cos 45° = √2/2 and in 0° ≤ θ ≤ 180° the only solution is 45°).