If sin 2A = 2 sin A cos A, what is the value of sin 2A when sin A = 1/2?

Practice Questions

Q1
If sin 2A = 2 sin A cos A, what is the value of sin 2A when sin A = 1/2?
  1. 1/2
  2. 1
  3. √3/2
  4. 0

Questions & Step-by-Step Solutions

If sin 2A = 2 sin A cos A, what is the value of sin 2A when sin A = 1/2?
  • Step 1: Identify the given value. We know that sin A = 1/2.
  • Step 2: Use the double angle formula for sine, which is sin 2A = 2 sin A cos A.
  • Step 3: Substitute sin A into the formula. Since sin A = 1/2, we have sin 2A = 2(1/2) cos A.
  • Step 4: Calculate cos A. We know that sin² A + cos² A = 1. So, (1/2)² + cos² A = 1.
  • Step 5: Simplify the equation. (1/4) + cos² A = 1, which means cos² A = 1 - 1/4 = 3/4.
  • Step 6: Take the square root to find cos A. cos A = √(3/4) = √3/2.
  • Step 7: Substitute cos A back into the double angle formula. Now we have sin 2A = 2(1/2)(√3/2).
  • Step 8: Simplify the expression. sin 2A = 1 * (√3/2) = √3/2.
  • Double Angle Formula – The question tests the understanding of the double angle formula for sine, which states that sin 2A = 2 sin A cos A.
  • Trigonometric Values – It assesses the ability to substitute known values of sine and calculate the corresponding cosine value.
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