Answer: 1.
- A 1/6
- B 1
- C 5/6
- D 1/2
Correct answer: B. 1
Explanation: tan(A+B) = (tanA + tanB)/(1 - tanA tanB) = (1/2+1/3)/(1-1/6) = (5/6)/(5/6) = 1. So A+B = 45°.
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