If the vector a = (2, -1) and b = (1, 3), what is the cross product a × b?

Practice Questions

Q1
If the vector a = (2, -1) and b = (1, 3), what is the cross product a × b?
  1. 5
  2. 7
  3. 1
  4. 0

Questions & Step-by-Step Solutions

If the vector a = (2, -1) and b = (1, 3), what is the cross product a × b?
  • Step 1: Identify the components of vector a. Here, a = (2, -1) means a1 = 2 and a2 = -1.
  • Step 2: Identify the components of vector b. Here, b = (1, 3) means b1 = 1 and b2 = 3.
  • Step 3: Use the formula for the cross product in 2D, which is a1 * b2 - a2 * b1.
  • Step 4: Substitute the values into the formula: 2 * 3 - (-1) * 1.
  • Step 5: Calculate 2 * 3, which equals 6.
  • Step 6: Calculate -(-1) * 1, which equals 1.
  • Step 7: Add the results from Step 5 and Step 6: 6 + 1 = 7.
  • Step 8: The final result of the cross product a × b is 7.
  • Cross Product in 2D – The cross product of two vectors in 2D is calculated using the formula a1*b2 - a2*b1, which results in a scalar value.
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