Answer: 8.
- A 4
- B 8
- C 6
- D 12
Correct answer: B. 8
Explanation: Sine rule states a/sinA=b/sinB=c/sinC=2R (R=circumradius). Substituting a=8, A=30°: 2R=8/sin30°=8/(1/2)=16, so R=8. The circumscribed circle of this triangle has radius 8.
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