Porisma

A hint to get started

Use a diagonal direction for a line and a parallelogram area

Relative to O, A,B,C have position vectors i+6j−2k\mathbf i+6\mathbf j-2\mathbf k, −3i+2j−5k-3\mathbf i+2\mathbf j-5\mathbf k, 3i−2j+2k3\mathbf i-2\mathbf j+2\mathbf k. L passes through A,C.

(i) Find a vector equation of L. marks

(ii) Find the exact length of projection of AB onto L. marks

(iii) Hence or otherwise find the shortest distance from B to L in exact form. marks

D is such that ABCD is a parallelogram. Use a vector product to find its exact area. marks

[2012/IJC/Promo/10]

CJC · Review problems · Question 3

Subtract A from C to form L; subtract A from B for the displacement being projected.

Read the worked solution