BITSAT 2018 Paper

Let A = (3, 4, 5), P = (–1, 2, 4)
B = (4, 6, 3) and Q = (1, 0, 5)
∴ Dr's of line AB are (4 – 3), (6 – 4), (3 – 5)= 1, 2, –2
and Dr's of line PQ are (1 + 1), (0 – 2), (5 – 4)= 2, –2, 1
∴ Dc's of line PQ =

2

√22+(−2)2+1

, −

2

3

,

1

3

=

2

3

,−

2

3

,

1

3

∴ Projection of line segment AB on the line PQis |

2

3

(1)+(−

2

3

)(2)+(

1

3

)(−2)| =

4

3