Answer: sqrt(3)/2.
- A 1/2
- B 1
- C sqrt(3)
- D sqrt(3)/2
Correct answer: D. sqrt(3)/2
Explanation: AB = B−A = (−1,1,0), AC = C−A = (−1,0,1). Cross product AB×AC = |i j k; −1 1 0; −1 0 1| = (1,1,1). |AB×AC| = √3. Area = ½√3 = √3/2. Answer: √3/2.
Triangle law of vector addition: placing vector b at the head of vector a, the diagonal from the start to the final head gives the resultant a + b.
Concept context
Vectors, dot product, cross product, and geometric applications