Answer: 1/√2.
- A 1/2
- B 1/√2
- C √3/2
- D 1
Correct answer: B. 1/√2
Explanation: cos 45° = 1/sqrt(2) = sqrt(2)/2. Isosceles right triangle.
Unit circle with standard angles 0, 30, 45, 60, 90 degrees; at 45 degrees the point is (cos45, sin45) = (1/sqrt2, 1/sqrt2).
Concept context
Ratios, identities, and applications in triangles