Originally Posted by AZKAFATIMA

Three vectors are given by:
a = 3i + 3j -2k
b = -i - 4j + 2k
c = 2i + 2j – k
Find (i) a. (b. × c), (ii) a. (b. + c), (iii) a. × (b + c)

The problem is written as (b. × c) it must be either (b × c or b . c). Am i right?


I have tried the first one through matrices and the simple cross method the answer is (b × c)= 3j + 6k
or it is b . c thats why i am getting the wrong answer. Resolve issues.

The second is

find the value of e so that A = ci – 2j + k and B = 2ci + cj – 4k are perpendicular.

Its not e its c. I solved it by dot product as

********* A . B = ABcos90°= 0 because A B are perpendicular. But didn,t get the answer.****

Regards.