Question

If A vector =i cap+2j cap+k cap,B vector =2 icap+2 kcap and C Vector=-2i cap+4k cap then magnitude of vector A+ Vector B- Vector C is
1)Root 20
2)Root 30
3)Root 65
4)Root 69

Answer 1

Answer:

Given, a=2i+2j+3k,b=−1+2j+k and c=3i+j

We need to find value of a+tb⊥c

⇒(a+tb)⋅c=0

⇒a⋅c+tb⋅c=0

⇒t=−

b⋅c

a⋅c

⇒t=−

(−i+2j+k)⋅(3i+j)

(2i+2j+3k)⋅(3i+j)

⇒t=−

−3+2+0

6+2+0

=8