H2 Maths 3.2 - Scalar and Vector Products Worked Example

What you will learn

• OA = a = (1, 2, -2) and OB = b = (3, -1, 1); goal is dot product, vector product, and area of triangle OAB.
• Dot product a . b = 1(3) + 2(-1) + (-2)(1) = -1; |a| = 3, |b| = sqrt(11), giving angle about 95.8 degrees (obtuse matches the negative dot).
• Cross product a x b = (0, -7, -7); magnitude sqrt(98) = 7 sqrt(2).