- Asin(A/2)
- Bcos(A/2)
- C−cos(A/2)
- DcosA
Step-by-Step Solution
Since A + B + C = 180°, we get (B + C)/2 = 90° − A/2. Therefore sin((B + C)/2) = sin(90° − A/2) = cos(A/2).
Answer: B) cos(A/2)
If A, B and C are the three angles of a triangle, then sin((B + C)/2) equals:
Competition practiceTrigonometry
Master this topic in 30 minutes a day.
Don't just memorise the answer — build a daily practice habit.
Practice 5 Similar Questions Free →All Trigonometry practice questions
More Trigonometry practice
If sinθ = 12/13 and θ is acute, the value of cosecθ + cotθ is:The sum of all values of θ in 0° ≤ θ ≤ 90° that satisfy 2sin²θ − 3sinθ + 1 = 0 is:For 0° < θ < 90°, which statement is FALSE?If A + B = 180°, then sinA·cosB + cosA·sinB equals:For how many values of θ with 0° ≤ θ < 360° does 4sinθ + 3cosθ = 6 hold?