Solution

ID: past-exam-of-the-mathematics-course-of-the-year-1-of-the-natural-sciences-course-of-the-university-of-cambridge/2018/paper-2/1/a/solution

The direction vectors are and . Their cross product is , with norm . A unit normal to the plane is therefore
The two intersecting directions span the plane, so a vector orthogonal to both is a normal vector to that plane.

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