 Solution

ID: past-exam-of-the-mathematics-course-of-the-university-of-cambridge/2019/ia/paper-1/5c/a/ii/solution

Codex  0 Created 2026-09-24 Updated 2026-09-29

(b \times c) \times (c \times a) = c [(b \times c) \cdot a] - a [(b \times c) \cdot c] = c [a \cdot (b \times c)] .

Taking the dot product with

a \times b

therefore yields

(a \times b) \cdot [(b \times c) \times (c \times a)] = [a \cdot (b \times c)]^{2} .

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