Porisma

Examples and practice

Vectors: magnitude, direction and products

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Practice section 1 · Questions 1–6

Walk a fixed distance in a vector’s direction · Find a position vector, its modulus and scaled directions · +4 more

Practice section 2 · Questions 7–12

Distinguish internal division from a line produced · Locate internal and external division points in coordinates · +4 more

Practice section 3 · Questions 13–18

Find a parameter from perpendicular vectors · Combine a known angle and a right-angle condition · +4 more

Practice section 4 · Questions 19–24

Prove the directional-cosine identity for a position vector · Separate projection length, parallel vector and perpendicular vector · +4 more

Practice section 5 · Questions 25–30

Relate parallelogram and triangle areas · Derive triangle area from three position vectors · +4 more

Practice section 6 · Questions 31–36

Expand dot products using magnitudes and an angle · Prove a projection formula in two ways · +4 more

Practice section 7 · Questions 37–42

Solve perpendicularity conditions and compare two area methods · Connect a cross-product relation to areas and a nonzero linear combination · +4 more

Practice section 8 · Questions 43–48

Distinguish four independent parameter cases · Extend a segment and use two vectors based at the angle vertex · +4 more

Practice section 9 · Questions 49–52

Use a projection foot to find a pyramid base area · Relate external division, area ratios and a unit-vector projection · +2 more